webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

14 files changed, 724 insertions, 1569 deletions

diff --git a/Source/WebCore/history/BackForwardClient.h b/Source/WebCore/history/BackForwardClient.h
index 8ba55e578..f1bafdecc 100644
--- a/Source/WebCore/history/BackForwardClient.h
+++ b/Source/WebCore/history/BackForwardClient.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006, 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2006, 2010, 2016 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2009 Google, Inc. All rights reserved.
  *
@@ -12,10 +12,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -25,8 +25,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
-#ifndef BackForwardClient_h
-#define BackForwardClient_h
+#pragma once
 
 #include <wtf/Forward.h>
 #include <wtf/RefCounted.h>
@@ -41,7 +40,7 @@ public:
     {
     }
 
-    virtual void addItem(PassRefPtr<HistoryItem>) = 0;
+    virtual void addItem(Ref<HistoryItem>&&) = 0;
 
     virtual void goToItem(HistoryItem*) = 0;
         
@@ -50,23 +49,6 @@ public:
     virtual int forwardListCount() = 0;
 
     virtual void close() = 0;
-
-#if PLATFORM(IOS)
-    // FIXME: These methods seem to violate the encapsulation of this class.
-    virtual unsigned current() = 0;
-    virtual void setCurrent(unsigned newCurrent) = 0;
-
-    // FIXME: Consider renaming this method once we upstream the iOS changes to WebView.mm.
-    virtual bool clearAllPageCaches() = 0;
-#endif
-
-    // FIXME: Delete these once all callers are using BackForwardController
-    // instead of calling this directly.
-    HistoryItem* backItem() { return itemAtIndex(-1); }
-    HistoryItem* currentItem() { return itemAtIndex(0); }
-    HistoryItem* forwardItem() { return itemAtIndex(1); }
 };
 
 } // namespace WebCore
-
-#endif // BackForwardClient_h
diff --git a/Source/WebCore/history/BackForwardController.cpp b/Source/WebCore/history/BackForwardController.cpp
index 2d1d02009..1bc8b5a5f 100644
--- a/Source/WebCore/history/BackForwardController.cpp
+++ b/Source/WebCore/history/BackForwardController.cpp
@@ -26,18 +26,15 @@
 #include "config.h"
 #include "BackForwardController.h"
 
-#include "BackForwardList.h"
-#include "HistoryItem.h"
+#include "BackForwardClient.h"
 #include "Page.h"
 
 namespace WebCore {
 
-BackForwardController::BackForwardController(Page& page, PassRefPtr<BackForwardClient> client)
+BackForwardController::BackForwardController(Page& page, Ref<BackForwardClient>&& client)
     : m_page(page)
-    , m_client(client)
+    , m_client(WTFMove(client))
 {
-    if (!m_client)
-        m_client = BackForwardList::create(&page);
 }
 
 BackForwardController::~BackForwardController()
@@ -74,7 +71,7 @@ void BackForwardController::goBackOrForward(int distance)
     if (!item)
         return;
 
-    m_page.goToItem(item, FrameLoadTypeIndexedBackForward);
+    m_page.goToItem(*item, FrameLoadType::IndexedBackForward);
 }
 
 bool BackForwardController::goBack()
@@ -83,7 +80,7 @@ bool BackForwardController::goBack()
     if (!item)
         return false;
 
-    m_page.goToItem(item, FrameLoadTypeBack);
+    m_page.goToItem(*item, FrameLoadType::Back);
     return true;
 }
 
@@ -93,13 +90,13 @@ bool BackForwardController::goForward()
     if (!item)
         return false;
 
-    m_page.goToItem(item, FrameLoadTypeForward);
+    m_page.goToItem(*item, FrameLoadType::Forward);
     return true;
 }
 
-void BackForwardController::addItem(PassRefPtr<HistoryItem> item)
+void BackForwardController::addItem(Ref<HistoryItem>&& item)
 {
-    m_client->addItem(item);
+    m_client->addItem(WTFMove(item));
 }
 
 void BackForwardController::setCurrentItem(HistoryItem* item)
diff --git a/Source/WebCore/history/BackForwardController.h b/Source/WebCore/history/BackForwardController.h
index 638774643..60693d788 100644
--- a/Source/WebCore/history/BackForwardController.h
+++ b/Source/WebCore/history/BackForwardController.h
@@ -23,8 +23,7 @@
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef BackForwardController_h
-#define BackForwardController_h
+#pragma once
 
 #include <wtf/Noncopyable.h>
 #include <wtf/Forward.h>
@@ -39,25 +38,25 @@ class Page;
 class BackForwardController {
     WTF_MAKE_NONCOPYABLE(BackForwardController); WTF_MAKE_FAST_ALLOCATED;
 public:
-    BackForwardController(Page&, PassRefPtr<BackForwardClient>);
+    BackForwardController(Page&, Ref<BackForwardClient>&&);
     ~BackForwardController();
 
     BackForwardClient* client() const { return m_client.get(); }
 
-    bool canGoBackOrForward(int distance) const;
+    WEBCORE_EXPORT bool canGoBackOrForward(int distance) const;
     void goBackOrForward(int distance);
 
-    bool goBack();
-    bool goForward();
+    WEBCORE_EXPORT bool goBack();
+    WEBCORE_EXPORT bool goForward();
 
-    void addItem(PassRefPtr<HistoryItem>);
+    void addItem(Ref<HistoryItem>&&);
     void setCurrentItem(HistoryItem*);
         
     int count() const;
-    int backCount() const;
-    int forwardCount() const;
+    WEBCORE_EXPORT int backCount() const;
+    WEBCORE_EXPORT int forwardCount() const;
 
-    HistoryItem* itemAtIndex(int);
+    WEBCORE_EXPORT HistoryItem* itemAtIndex(int);
 
     void close();
 
@@ -71,5 +70,3 @@ private:
 };
 
 } // namespace WebCore
-
-#endif // BackForwardController_h
diff --git a/Source/WebCore/history/BackForwardList.cpp b/Source/WebCore/history/BackForwardList.cpp
deleted file mode 100644
index b031ef16d..000000000
--- a/Source/WebCore/history/BackForwardList.cpp
+++ /dev/null
@@ -1,300 +0,0 @@
-/*
- * Copyright (C) 2005, 2006 Apple Computer, Inc.  All rights reserved.
- * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
- */
-
-#include "config.h"
-#include "BackForwardList.h"
-
-#include "Frame.h"
-#include "FrameLoader.h"
-#include "FrameLoaderClient.h"
-#include "HistoryItem.h"
-#include "Logging.h"
-#include "Page.h"
-#include "PageCache.h"
-#include "SerializedScriptValue.h"
-
-namespace WebCore {
-
-static const unsigned DefaultCapacity = 100;
-static const unsigned NoCurrentItemIndex = UINT_MAX;
-
-BackForwardList::BackForwardList(Page* page)
-    : m_page(page)
-    , m_current(NoCurrentItemIndex)
-    , m_capacity(DefaultCapacity)
-    , m_closed(true)
-    , m_enabled(true)
-{
-}
-
-BackForwardList::~BackForwardList()
-{
-    ASSERT(m_closed);
-}
-
-void BackForwardList::addItem(PassRefPtr<HistoryItem> prpItem)
-{
-    ASSERT(prpItem);
-    if (m_capacity == 0 || !m_enabled)
-        return;
-    
-    // Toss anything in the forward list    
-    if (m_current != NoCurrentItemIndex) {
-        unsigned targetSize = m_current + 1;
-        while (m_entries.size() > targetSize) {
-            RefPtr<HistoryItem> item = m_entries.last();
-            m_entries.removeLast();
-            m_entryHash.remove(item);
-            pageCache()->remove(item.get());
-        }
-    }
-
-    // Toss the first item if the list is getting too big, as long as we're not using it
-    // (or even if we are, if we only want 1 entry).
-    if (m_entries.size() == m_capacity && (m_current != 0 || m_capacity == 1)) {
-        RefPtr<HistoryItem> item = m_entries[0];
-        m_entries.remove(0);
-        m_entryHash.remove(item);
-        pageCache()->remove(item.get());
-        m_current--;
-    }
-
-    m_entryHash.add(prpItem.get());
-    m_entries.insert(m_current + 1, prpItem);
-    m_current++;
-}
-
-void BackForwardList::goBack()
-{
-    ASSERT(m_current > 0);
-    if (m_current > 0) {
-        m_current--;
-    }
-}
-
-void BackForwardList::goForward()
-{
-    ASSERT(m_current < m_entries.size() - 1);
-    if (m_current < m_entries.size() - 1) {
-        m_current++;
-    }
-}
-
-void BackForwardList::goToItem(HistoryItem* item)
-{
-    if (!m_entries.size() || !item)
-        return;
-        
-    unsigned int index = 0;
-    for (; index < m_entries.size(); ++index)
-        if (m_entries[index] == item)
-            break;
-    if (index < m_entries.size()) {
-        m_current = index;
-    }
-}
-
-HistoryItem* BackForwardList::backItem()
-{
-    if (m_current && m_current != NoCurrentItemIndex)
-        return m_entries[m_current - 1].get();
-    return 0;
-}
-
-HistoryItem* BackForwardList::currentItem()
-{
-    if (m_current != NoCurrentItemIndex)
-        return m_entries[m_current].get();
-    return 0;
-}
-
-HistoryItem* BackForwardList::forwardItem()
-{
-    if (m_entries.size() && m_current < m_entries.size() - 1)
-        return m_entries[m_current + 1].get();
-    return 0;
-}
-
-void BackForwardList::backListWithLimit(int limit, HistoryItemVector& list)
-{
-    list.clear();
-    if (m_current != NoCurrentItemIndex) {
-        unsigned first = std::max((int)m_current - limit, 0);
-        for (; first < m_current; ++first)
-            list.append(m_entries[first]);
-    }
-}
-
-void BackForwardList::forwardListWithLimit(int limit, HistoryItemVector& list)
-{
-    ASSERT(limit > -1);
-    list.clear();
-    if (!m_entries.size())
-        return;
-        
-    unsigned lastEntry = m_entries.size() - 1;
-    if (m_current < lastEntry) {
-        int last = std::min(m_current + limit, lastEntry);
-        limit = m_current + 1;
-        for (; limit <= last; ++limit)
-            list.append(m_entries[limit]);
-    }
-}
-
-int BackForwardList::capacity()
-{
-    return m_capacity;
-}
-
-void BackForwardList::setCapacity(int size)
-{    
-    while (size < (int)m_entries.size()) {
-        RefPtr<HistoryItem> item = m_entries.last();
-        m_entries.removeLast();
-        m_entryHash.remove(item);
-        pageCache()->remove(item.get());
-    }
-
-    if (!size)
-        m_current = NoCurrentItemIndex;
-    else if (m_current > m_entries.size() - 1) {
-        m_current = m_entries.size() - 1;
-    }
-    m_capacity = size;
-}
-
-bool BackForwardList::enabled()
-{
-    return m_enabled;
-}
-
-void BackForwardList::setEnabled(bool enabled)
-{
-    m_enabled = enabled;
-    if (!enabled) {
-        int capacity = m_capacity;
-        setCapacity(0);
-        setCapacity(capacity);
-    }
-}
-
-int BackForwardList::backListCount()
-{
-    return m_current == NoCurrentItemIndex ? 0 : m_current;
-}
-
-int BackForwardList::forwardListCount()
-{
-    return m_current == NoCurrentItemIndex ? 0 : (int)m_entries.size() - (m_current + 1);
-}
-
-HistoryItem* BackForwardList::itemAtIndex(int index)
-{
-    // Do range checks without doing math on index to avoid overflow.
-    if (index < -(int)m_current)
-        return 0;
-    
-    if (index > forwardListCount())
-        return 0;
-        
-    return m_entries[index + m_current].get();
-}
-
-HistoryItemVector& BackForwardList::entries()
-{
-    return m_entries;
-}
-
-#if PLATFORM(IOS)
-unsigned BackForwardList::current()
-{
-    return m_current;
-}
-
-void BackForwardList::setCurrent(unsigned newCurrent)
-{
-    m_current = newCurrent;
-}
-
-bool BackForwardList::clearAllPageCaches()
-{
-    bool didRemoveAtLeastOneItem = false;
-    unsigned length = m_entries.size();
-    for (unsigned i = 0; i < length; ++i) {
-        HistoryItem* item = m_entries[i].get();
-        if (item->isInPageCache()) {
-            didRemoveAtLeastOneItem = true;
-            pageCache()->remove(item);
-        }
-    }
-    return didRemoveAtLeastOneItem;
-}
-#endif
-
-void BackForwardList::close()
-{
-    int size = m_entries.size();
-    for (int i = 0; i < size; ++i)
-        pageCache()->remove(m_entries[i].get());
-    m_entries.clear();
-    m_entryHash.clear();
-    m_page = 0;
-    m_closed = true;
-}
-
-bool BackForwardList::closed()
-{
-    return m_closed;
-}
-
-void BackForwardList::removeItem(HistoryItem* item)
-{
-    if (!item)
-        return;
-    
-    for (unsigned i = 0; i < m_entries.size(); ++i)
-        if (m_entries[i] == item) {
-            m_entries.remove(i);
-            m_entryHash.remove(item);
-            if (m_current == NoCurrentItemIndex || m_current < i)
-                break;
-            if (m_current > i)
-                m_current--;
-            else {
-                size_t count = m_entries.size();
-                if (m_current >= count)
-                    m_current = count ? count - 1 : NoCurrentItemIndex;
-            }
-            break;
-        }
-}
-
-bool BackForwardList::containsItem(HistoryItem* entry)
-{
-    return m_entryHash.contains(entry);
-}
-
-}; // namespace WebCore
diff --git a/Source/WebCore/history/BackForwardList.h b/Source/WebCore/history/BackForwardList.h
deleted file mode 100644
index ae7adfa16..000000000
--- a/Source/WebCore/history/BackForwardList.h
+++ /dev/null
@@ -1,97 +0,0 @@
-/*
- * Copyright (C) 2006, 2010 Apple Inc. All rights reserved.
- * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
- * Copyright (C) 2009 Google, Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
- */
-
-#ifndef BackForwardList_h
-#define BackForwardList_h
-
-#include "BackForwardClient.h"
-#include <wtf/HashSet.h>
-#include <wtf/Vector.h>
-
-namespace WebCore {
-
-class Page;
-
-typedef Vector<RefPtr<HistoryItem>> HistoryItemVector;
-typedef HashSet<RefPtr<HistoryItem>> HistoryItemHashSet;
-
-class BackForwardList : public BackForwardClient {
-public: 
-    static PassRefPtr<BackForwardList> create(Page* page) { return adoptRef(new BackForwardList(page)); }
-    virtual ~BackForwardList();
-
-    Page* page() { return m_page; }
-
-    virtual void addItem(PassRefPtr<HistoryItem>) override;
-    void goBack();
-    void goForward();
-    virtual void goToItem(HistoryItem*) override;
-        
-    HistoryItem* backItem();
-    HistoryItem* currentItem();
-    HistoryItem* forwardItem();
-    virtual HistoryItem* itemAtIndex(int) override;
-
-    void backListWithLimit(int, HistoryItemVector&);
-    void forwardListWithLimit(int, HistoryItemVector&);
-
-    int capacity();
-    void setCapacity(int);
-    bool enabled();
-    void setEnabled(bool);
-    virtual int backListCount() override;
-    virtual int forwardListCount() override;
-    bool containsItem(HistoryItem*);
-
-    virtual void close() override;
-    bool closed();
-
-    void removeItem(HistoryItem*);
-    HistoryItemVector& entries();
-
-#if PLATFORM(IOS)
-    virtual unsigned current() override;
-    virtual void setCurrent(unsigned newCurrent) override;
-
-    virtual bool clearAllPageCaches() override;
-#endif
-
-private:
-    explicit BackForwardList(Page*);
-
-    Page* m_page;
-    HistoryItemVector m_entries;
-    HistoryItemHashSet m_entryHash;
-    unsigned m_current;
-    unsigned m_capacity;
-    bool m_closed;
-    bool m_enabled;
-};
-    
-} // namespace WebCore
-
-#endif // BackForwardList_h
diff --git a/Source/WebCore/history/CachedFrame.cpp b/Source/WebCore/history/CachedFrame.cpp
index 1f61671d7..210285243 100644
--- a/Source/WebCore/history/CachedFrame.cpp
+++ b/Source/WebCore/history/CachedFrame.cpp
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -24,44 +24,32 @@
  */
  
 #include "config.h"
-#include "CachedPage.h"
+#include "CachedFrame.h"
 
-#include "AnimationController.h"
+#include "CSSAnimationController.h"
 #include "CachedFramePlatformData.h"
+#include "CachedPage.h"
 #include "DOMWindow.h"
 #include "Document.h"
 #include "DocumentLoader.h"
-#include "EventHandler.h"
-#include "EventNames.h"
-#include "ExceptionCode.h"
-#include "FocusController.h"
 #include "FrameLoader.h"
 #include "FrameLoaderClient.h"
 #include "FrameView.h"
-#include "HistoryController.h"
-#include "HistoryItem.h"
 #include "Logging.h"
 #include "MainFrame.h"
 #include "Page.h"
-#include "PageTransitionEvent.h"
+#include "PageCache.h"
+#include "SVGDocumentExtensions.h"
 #include "ScriptController.h"
 #include "SerializedScriptValue.h"
 #include <wtf/RefCountedLeakCounter.h>
 #include <wtf/text/CString.h>
 
-#if ENABLE(SVG)
-#include "SVGDocumentExtensions.h"
-#endif
-
-#if ENABLE(TOUCH_EVENTS)
+#if PLATFORM(IOS) || ENABLE(TOUCH_EVENTS)
 #include "Chrome.h"
 #include "ChromeClient.h"
 #endif
 
-#if USE(ACCELERATED_COMPOSITING)
-#include "PageCache.h"
-#endif
-
 namespace WebCore {
 
 DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, cachedFrameCounter, ("CachedFrame"));
@@ -70,12 +58,8 @@ CachedFrameBase::CachedFrameBase(Frame& frame)
     : m_document(frame.document())
     , m_documentLoader(frame.loader().documentLoader())
     , m_view(frame.view())
-    , m_mousePressNode(frame.eventHandler().mousePressNode())
     , m_url(frame.document()->url())
     , m_isMainFrame(!frame.tree().parent())
-#if USE(ACCELERATED_COMPOSITING)
-    , m_isComposited(frame.view()->hasCompositedContent())
-#endif
 {
 }
 
@@ -88,6 +72,17 @@ CachedFrameBase::~CachedFrameBase()
     ASSERT(!m_document);
 }
 
+void CachedFrameBase::pruneDetachedChildFrames()
+{
+    for (size_t i = m_childFrames.size(); i;) {
+        --i;
+        if (m_childFrames[i]->view()->frame().page())
+            continue;
+        m_childFrames[i]->destroy();
+        m_childFrames.remove(i);
+    }
+}
+
 void CachedFrameBase::restore()
 {
     ASSERT(m_document->view() == m_view);
@@ -98,31 +93,27 @@ void CachedFrameBase::restore()
     Frame& frame = m_view->frame();
     m_cachedFrameScriptData->restore(frame);
 
-#if ENABLE(SVG)
     if (m_document->svgExtensions())
-        m_document->accessSVGExtensions()->unpauseAnimations();
-#endif
+        m_document->accessSVGExtensions().unpauseAnimations();
 
     frame.animation().resumeAnimationsForDocument(m_document.get());
-    frame.eventHandler().setMousePressNode(m_mousePressNode.get());
-    m_document->resumeActiveDOMObjects(ActiveDOMObject::DocumentWillBecomeInactive);
-    m_document->resumeScriptedAnimationControllerCallbacks();
+
+    m_document->resume(ActiveDOMObject::PageCache);
 
     // It is necessary to update any platform script objects after restoring the
     // cached page.
     frame.script().updatePlatformScriptObjects();
 
-#if USE(ACCELERATED_COMPOSITING)
-    if (m_isComposited)
-        frame.view()->restoreBackingStores();
-#endif
-
     frame.loader().client().didRestoreFromPageCache();
 
+    pruneDetachedChildFrames();
+
     // Reconstruct the FrameTree. And open the child CachedFrames in their respective FrameLoaders.
-    for (unsigned i = 0; i < m_childFrames.size(); ++i) {
-        frame.tree().appendChild(&m_childFrames[i]->view()->frame());
-        m_childFrames[i]->open();
+    for (auto& childFrame : m_childFrames) {
+        ASSERT(childFrame->view()->frame().page());
+        frame.tree().appendChild(childFrame->view()->frame());
+        childFrame->open();
+        ASSERT_WITH_SECURITY_IMPLICATION(m_document == frame.document());
     }
 
 #if PLATFORM(IOS)
@@ -131,25 +122,14 @@ void CachedFrameBase::restore()
 
         if (DOMWindow* domWindow = m_document->domWindow()) {
             // FIXME: Add SCROLL_LISTENER to the list of event types on Document, and use m_document->hasListenerType(). See <rdar://problem/9615482>.
+            // FIXME: Can use Document::hasListenerType() now.
             if (domWindow->scrollEventListenerCount() && frame.page())
-                frame.page()->chrome().client().setNeedsScrollNotifications(&frame, true);
+                frame.page()->chrome().client().setNeedsScrollNotifications(frame, true);
         }
     }
 #endif
 
-    // FIXME: update Page Visibility state here.
-    // https://bugs.webkit.org/show_bug.cgi?id=116770
-    m_document->enqueuePageshowEvent(PageshowEventPersisted);
-
-    HistoryItem* historyItem = frame.loader().history().currentItem();
-    m_document->enqueuePopstateEvent(historyItem && historyItem->stateObject() ? historyItem->stateObject() : SerializedScriptValue::nullValue());
-
-#if ENABLE(TOUCH_EVENTS) && !PLATFORM(IOS)
-    if (m_document->hasTouchEventHandlers())
-        m_document->page()->chrome().client().needTouchEvents(true);
-#endif
-
-    m_document->documentDidResumeFromPageCache();
+    frame.view()->didRestoreFromPageCache();
 }
 
 CachedFrame::CachedFrame(Frame& frame)
@@ -161,38 +141,21 @@ CachedFrame::CachedFrame(Frame& frame)
     ASSERT(m_document);
     ASSERT(m_documentLoader);
     ASSERT(m_view);
-
-    if (frame.page()->focusController().focusedFrame() == &frame)
-        frame.page()->focusController().setFocusedFrame(&frame.mainFrame());
-
-    // Custom scrollbar renderers will get reattached when the document comes out of the page cache
-    m_view->detachCustomScrollbars();
-
-    m_document->setInPageCache(true);
-    frame.loader().stopLoading(UnloadEventPolicyUnloadAndPageHide);
+    ASSERT(m_document->pageCacheState() == Document::InPageCache);
 
     // Create the CachedFrames for all Frames in the FrameTree.
     for (Frame* child = frame.tree().firstChild(); child; child = child->tree().nextSibling())
         m_childFrames.append(std::make_unique<CachedFrame>(*child));
 
-    // Active DOM objects must be suspended before we cache the frame script data,
-    // but after we've fired the pagehide event, in case that creates more objects.
-    // Suspending must also happen after we've recursed over child frames, in case
-    // those create more objects.
-    m_document->documentWillSuspendForPageCache();
-    m_document->suspendScriptedAnimationControllerCallbacks();
-    m_document->suspendActiveDOMObjects(ActiveDOMObject::DocumentWillBecomeInactive);
+    // Active DOM objects must be suspended before we cache the frame script data.
+    m_document->suspend(ActiveDOMObject::PageCache);
+
     m_cachedFrameScriptData = std::make_unique<ScriptCachedFrameData>(frame);
 
-    m_document->domWindow()->suspendForPageCache();
+    m_document->domWindow()->suspendForDocumentSuspension();
 
     frame.loader().client().savePlatformDataToCachedFrame(this);
 
-#if USE(ACCELERATED_COMPOSITING)
-    if (m_isComposited && pageCache()->shouldClearBackingStores())
-        frame.view()->clearBackingStores();
-#endif
-
     // documentWillSuspendForPageCache() can set up a layout timer on the FrameView, so clear timers after that.
     frame.clearTimers();
 
@@ -201,7 +164,7 @@ CachedFrame::CachedFrame(Frame& frame)
     // 1 - We reuse the main frame, so when it navigates to a new page load it needs to start with a blank FrameTree.
     // 2 - It's much easier to destroy a CachedFrame while it resides in the PageCache if it is disconnected from its parent.
     for (unsigned i = 0; i < m_childFrames.size(); ++i)
-        frame.tree().removeChild(&m_childFrames[i]->view()->frame());
+        frame.tree().removeChild(m_childFrames[i]->view()->frame());
 
     if (!m_isMainFrame)
         frame.page()->decrementSubframeCount();
@@ -219,18 +182,25 @@ CachedFrame::CachedFrame(Frame& frame)
     if (m_isMainFrame) {
         if (DOMWindow* domWindow = m_document->domWindow()) {
             if (domWindow->scrollEventListenerCount() && frame.page())
-                frame.page()->chrome().client().setNeedsScrollNotifications(&frame, false);
+                frame.page()->chrome().client().setNeedsScrollNotifications(frame, false);
         }
     }
 #endif
+
+    m_document->detachFromCachedFrame(*this);
+
+    ASSERT_WITH_SECURITY_IMPLICATION(!m_documentLoader->isLoading());
 }
 
 void CachedFrame::open()
 {
     ASSERT(m_view);
+    ASSERT(m_document);
     if (!m_isMainFrame)
         m_view->frame().page()->incrementSubframeCount();
 
+    m_document->attachToCachedFrame(*this);
+
     m_view->frame().loader().open(*this);
 }
 
@@ -243,7 +213,7 @@ void CachedFrame::clear()
     // This means the CachedFrame has been:
     // 1 - Successfully restore()'d by going back/forward.
     // 2 - destroy()'ed because the PageCache is pruning or the WebView was closed.
-    ASSERT(!m_document->inPageCache());
+    ASSERT(m_document->pageCacheState() == Document::NotInPageCache);
     ASSERT(m_view);
     ASSERT(!m_document->frame() || m_document->frame() == &m_view->frame());
 
@@ -252,7 +222,6 @@ void CachedFrame::clear()
 
     m_document = nullptr;
     m_view = nullptr;
-    m_mousePressNode = nullptr;
     m_url = URL();
 
     m_cachedFramePlatformData = nullptr;
@@ -265,15 +234,15 @@ void CachedFrame::destroy()
         return;
     
     // Only CachedFrames that are still in the PageCache should be destroyed in this manner
-    ASSERT(m_document->inPageCache());
+    ASSERT(m_document->pageCacheState() == Document::InPageCache);
     ASSERT(m_view);
-    ASSERT(m_document->frame() == &m_view->frame());
+    ASSERT(!m_document->frame());
 
     m_document->domWindow()->willDestroyCachedFrame();
 
-    if (!m_isMainFrame) {
-        m_view->frame().detachFromPage();
+    if (!m_isMainFrame && m_view->frame().page()) {
         m_view->frame().loader().detachViewsAndDocumentLoader();
+        m_view->frame().detachFromPage();
     }
     
     for (int i = m_childFrames.size() - 1; i >= 0; --i)
@@ -284,11 +253,13 @@ void CachedFrame::destroy()
 
     Frame::clearTimers(m_view.get(), m_document.get());
 
+    m_view->frame().animation().detachFromDocument(m_document.get());
+
     // FIXME: Why do we need to call removeAllEventListeners here? When the document is in page cache, this method won't work
     // fully anyway, because the document won't be able to access its DOMWindow object (due to being frameless).
     m_document->removeAllEventListeners();
 
-    m_document->setInPageCache(false);
+    m_document->setPageCacheState(Document::NotInPageCache);
     m_document->prepareForDestruction();
 
     clear();
@@ -296,7 +267,7 @@ void CachedFrame::destroy()
 
 void CachedFrame::setCachedFramePlatformData(std::unique_ptr<CachedFramePlatformData> data)
 {
-    m_cachedFramePlatformData = std::move(data);
+    m_cachedFramePlatformData = WTFMove(data);
 }
 
 CachedFramePlatformData* CachedFrame::cachedFramePlatformData()
@@ -304,6 +275,11 @@ CachedFramePlatformData* CachedFrame::cachedFramePlatformData()
     return m_cachedFramePlatformData.get();
 }
 
+void CachedFrame::setHasInsecureContent(HasInsecureContent hasInsecureContent)
+{
+    m_hasInsecureContent = hasInsecureContent;
+}
+
 int CachedFrame::descendantFrameCount() const
 {
     int count = m_childFrames.size();
diff --git a/Source/WebCore/history/CachedFrame.h b/Source/WebCore/history/CachedFrame.h
index e9f367bbd..e0be571a2 100644
--- a/Source/WebCore/history/CachedFrame.h
+++ b/Source/WebCore/history/CachedFrame.h
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -23,8 +23,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
  
-#ifndef CachedFrame_h
-#define CachedFrame_h
+#pragma once
 
 #include "DOMWindow.h"
 #include "URL.h"
@@ -39,6 +38,7 @@ class Document;
 class DocumentLoader;
 class FrameView;
 class Node;
+enum class HasInsecureContent;
 
 class CachedFrameBase {
 public:
@@ -52,23 +52,23 @@ public:
 protected:
     CachedFrameBase(Frame&);
     ~CachedFrameBase();
-    
+
+    void pruneDetachedChildFrames();
+
     RefPtr<Document> m_document;
     RefPtr<DocumentLoader> m_documentLoader;
     RefPtr<FrameView> m_view;
-    RefPtr<Node> m_mousePressNode;
     URL m_url;
     std::unique_ptr<ScriptCachedFrameData> m_cachedFrameScriptData;
     std::unique_ptr<CachedFramePlatformData> m_cachedFramePlatformData;
     bool m_isMainFrame;
-#if USE(ACCELERATED_COMPOSITING)
-    bool m_isComposited;
-#endif
-    
+    std::optional<HasInsecureContent> m_hasInsecureContent;
+
     Vector<std::unique_ptr<CachedFrame>> m_childFrames;
 };
 
 class CachedFrame : private CachedFrameBase {
+    WTF_MAKE_FAST_ALLOCATED;
 public:
     explicit CachedFrame(Frame&);
 
@@ -76,18 +76,18 @@ public:
     void clear();
     void destroy();
 
-    void setCachedFramePlatformData(std::unique_ptr<CachedFramePlatformData>);
-    CachedFramePlatformData* cachedFramePlatformData();
+    WEBCORE_EXPORT void setCachedFramePlatformData(std::unique_ptr<CachedFramePlatformData>);
+    WEBCORE_EXPORT CachedFramePlatformData* cachedFramePlatformData();
+
+    WEBCORE_EXPORT void setHasInsecureContent(HasInsecureContent);
+    std::optional<HasInsecureContent> hasInsecureContent() const { return m_hasInsecureContent; }
 
     using CachedFrameBase::document;
     using CachedFrameBase::view;
     using CachedFrameBase::url;
     DocumentLoader* documentLoader() const { return m_documentLoader.get(); }
-    Node* mousePressNode() const { return m_mousePressNode.get(); }
 
     int descendantFrameCount() const;
 };
 
 } // namespace WebCore
-
-#endif // CachedFrame_h
diff --git a/Source/WebCore/history/CachedFramePlatformData.h b/Source/WebCore/history/CachedFramePlatformData.h
index 01da8e5a6..56f4431b9 100644
--- a/Source/WebCore/history/CachedFramePlatformData.h
+++ b/Source/WebCore/history/CachedFramePlatformData.h
@@ -10,7 +10,7 @@
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
- * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
@@ -25,8 +25,8 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-#ifndef CachedFramePlatformData_h
-#define CachedFramePlatformData_h
+
+#pragma once
 
 namespace WebCore {
 
@@ -41,5 +41,3 @@ public:
 };
 
 } // namespace WebCore
-
-#endif // CachedFramePlatformData_h
diff --git a/Source/WebCore/history/CachedPage.cpp b/Source/WebCore/history/CachedPage.cpp
index cad18497e..3ddd9c18d 100644
--- a/Source/WebCore/history/CachedPage.cpp
+++ b/Source/WebCore/history/CachedPage.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
+ * Copyright (C) 2006, 2007, 2008, 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -30,9 +30,13 @@
 #include "Element.h"
 #include "FocusController.h"
 #include "FrameView.h"
+#include "HistoryController.h"
+#include "HistoryItem.h"
 #include "MainFrame.h"
+#include "NoEventDispatchAssertion.h"
 #include "Node.h"
 #include "Page.h"
+#include "PageTransitionEvent.h"
 #include "Settings.h"
 #include "VisitedLinkState.h"
 #include <wtf/CurrentTime.h>
@@ -50,13 +54,9 @@ namespace WebCore {
 DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, cachedPageCounter, ("CachedPage"));
 
 CachedPage::CachedPage(Page& page)
-    : m_timeStamp(monotonicallyIncreasingTime())
-    , m_expirationTime(m_timeStamp + page.settings().backForwardCacheExpirationInterval())
+    : m_page(page)
+    , m_expirationTime(monotonicallyIncreasingTime() + page.settings().backForwardCacheExpirationInterval())
     , m_cachedMainFrame(std::make_unique<CachedFrame>(page.mainFrame()))
-    , m_needStyleRecalcForVisitedLinks(false)
-    , m_needsFullStyleRecalc(false)
-    , m_needsCaptionPreferencesChanged(false)
-    , m_needsDeviceScaleChanged(false)
 {
 #ifndef NDEBUG
     cachedPageCounter.increment();
@@ -69,8 +69,33 @@ CachedPage::~CachedPage()
     cachedPageCounter.decrement();
 #endif
 
-    destroy();
-    ASSERT(!m_cachedMainFrame);
+    if (m_cachedMainFrame)
+        m_cachedMainFrame->destroy();
+}
+
+static void firePageShowAndPopStateEvents(Page& page)
+{
+    // Dispatching JavaScript events can cause frame destruction.
+    auto& mainFrame = page.mainFrame();
+    Vector<Ref<Frame>> childFrames;
+    for (auto* child = mainFrame.tree().traverseNextInPostOrderWithWrap(true); child; child = child->tree().traverseNextInPostOrderWithWrap(false))
+        childFrames.append(*child);
+
+    for (auto& child : childFrames) {
+        if (!child->tree().isDescendantOf(&mainFrame))
+            continue;
+        auto* document = child->document();
+        if (!document)
+            continue;
+
+        // FIXME: Update Page Visibility state here.
+        // https://bugs.webkit.org/show_bug.cgi?id=116770
+        document->dispatchPageshowEvent(PageshowEventPersisted);
+
+        auto* historyItem = child->loader().history().currentItem();
+        if (historyItem && historyItem->stateObject())
+            document->dispatchPopstateEvent(historyItem->stateObject());
+    }
 }
 
 void CachedPage::restore(Page& page)
@@ -79,7 +104,13 @@ void CachedPage::restore(Page& page)
     ASSERT(m_cachedMainFrame->view()->frame().isMainFrame());
     ASSERT(!page.subframeCount());
 
-    m_cachedMainFrame->open();
+    {
+        // Do not dispatch DOM events as their JavaScript listeners could cause the page to be put
+        // into the page cache before we have finished restoring it from the page cache.
+        NoEventDispatchAssertion noEventDispatchAssertion;
+
+        m_cachedMainFrame->open();
+    }
     
     // Restore the focus appearance for the focused element.
     // FIXME: Right now we don't support pages w/ frames in the b/f cache.  This may need to be tweaked when we add support for that.
@@ -89,32 +120,39 @@ void CachedPage::restore(Page& page)
         // We don't want focused nodes changing scroll position when restoring from the cache
         // as it can cause ugly jumps before we manage to restore the cached position.
         page.mainFrame().selection().suppressScrolling();
+
+        bool hadProhibitsScrolling = false;
+        FrameView* frameView = page.mainFrame().view();
+        if (frameView) {
+            hadProhibitsScrolling = frameView->prohibitsScrolling();
+            frameView->setProhibitsScrolling(true);
+        }
 #endif
-        element->updateFocusAppearance(true);
+        element->updateFocusAppearance(SelectionRestorationMode::Restore);
 #if PLATFORM(IOS)
+        if (frameView)
+            frameView->setProhibitsScrolling(hadProhibitsScrolling);
         page.mainFrame().selection().restoreScrolling();
 #endif
     }
 
-    if (m_needStyleRecalcForVisitedLinks) {
-        for (Frame* frame = &page.mainFrame(); frame; frame = frame->tree().traverseNext())
-            frame->document()->visitedLinkState().invalidateStyleForAllLinks();
-    }
-
-#if USE(ACCELERATED_COMPOSITING)
-    if (m_needsDeviceScaleChanged) {
+    if (m_needsDeviceOrPageScaleChanged)
         page.mainFrame().deviceOrPageScaleFactorChanged();
-    }
-#endif
 
-    if (m_needsFullStyleRecalc)
-        page.setNeedsRecalcStyleInAllFrames();
+    page.setNeedsRecalcStyleInAllFrames();
 
 #if ENABLE(VIDEO_TRACK)
     if (m_needsCaptionPreferencesChanged)
         page.captionPreferencesChanged();
 #endif
 
+    if (m_needsUpdateContentsSize) {
+        if (FrameView* frameView = page.mainFrame().view())
+            frameView->updateContentsSize();
+    }
+
+    firePageShowAndPopStateEvents(page);
+
     clear();
 }
 
@@ -122,17 +160,12 @@ void CachedPage::clear()
 {
     ASSERT(m_cachedMainFrame);
     m_cachedMainFrame->clear();
-    m_cachedMainFrame = 0;
-    m_needStyleRecalcForVisitedLinks = false;
-    m_needsFullStyleRecalc = false;
-}
-
-void CachedPage::destroy()
-{
-    if (m_cachedMainFrame)
-        m_cachedMainFrame->destroy();
-
-    m_cachedMainFrame = 0;
+    m_cachedMainFrame = nullptr;
+#if ENABLE(VIDEO_TRACK)
+    m_needsCaptionPreferencesChanged = false;
+#endif
+    m_needsDeviceOrPageScaleChanged = false;
+    m_needsUpdateContentsSize = false;
 }
 
 bool CachedPage::hasExpired() const
diff --git a/Source/WebCore/history/CachedPage.h b/Source/WebCore/history/CachedPage.h
index bb83e0fff..73bdd5a9c 100644
--- a/Source/WebCore/history/CachedPage.h
+++ b/Source/WebCore/history/CachedPage.h
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -23,18 +23,18 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
-#ifndef CachedPage_h
-#define CachedPage_h
+#pragma once
 
 #include "CachedFrame.h"
 
 namespace WebCore {
-    
+
 class Document;
 class DocumentLoader;
 class Page;
 
 class CachedPage {
+    WTF_MAKE_FAST_ALLOCATED;
 public:
     explicit CachedPage(Page&);
     ~CachedPage();
@@ -42,37 +42,31 @@ public:
     void restore(Page&);
     void clear();
 
+    Page& page() const { return m_page; }
     Document* document() const { return m_cachedMainFrame->document(); }
     DocumentLoader* documentLoader() const { return m_cachedMainFrame->documentLoader(); }
 
-    double timeStamp() const { return m_timeStamp; }
     bool hasExpired() const;
     
     CachedFrame* cachedMainFrame() { return m_cachedMainFrame.get(); }
 
-    void markForVistedLinkStyleRecalc() { m_needStyleRecalcForVisitedLinks = true; }
-    void markForFullStyleRecalc() { m_needsFullStyleRecalc = true; }
 #if ENABLE(VIDEO_TRACK)
     void markForCaptionPreferencesChanged() { m_needsCaptionPreferencesChanged = true; }
 #endif
 
-#if USE(ACCELERATED_COMPOSITING)
-    void markForDeviceScaleChanged() { m_needsDeviceScaleChanged = true; }
-#endif
+    void markForDeviceOrPageScaleChanged() { m_needsDeviceOrPageScaleChanged = true; }
 
-private:
-    void destroy();
+    void markForContentsSizeChanged() { m_needsUpdateContentsSize = true; }
 
-    double m_timeStamp;
+private:
+    Page& m_page;
     double m_expirationTime;
     std::unique_ptr<CachedFrame> m_cachedMainFrame;
-    bool m_needStyleRecalcForVisitedLinks;
-    bool m_needsFullStyleRecalc;
-    bool m_needsCaptionPreferencesChanged;
-    bool m_needsDeviceScaleChanged;
+#if ENABLE(VIDEO_TRACK)
+    bool m_needsCaptionPreferencesChanged { false };
+#endif
+    bool m_needsDeviceOrPageScaleChanged { false };
+    bool m_needsUpdateContentsSize { false };
 };
 
 } // namespace WebCore
-
-#endif // CachedPage_h
-
diff --git a/Source/WebCore/history/HistoryItem.cpp b/Source/WebCore/history/HistoryItem.cpp
index 8ce0841b9..7a5fbbb45 100644
--- a/Source/WebCore/history/HistoryItem.cpp
+++ b/Source/WebCore/history/HistoryItem.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005, 2006, 2008, 2011 Apple Inc. All rights reserved.
+ * Copyright (C) 2005, 2006, 2008, 2011, 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -37,14 +37,10 @@
 #include <stdio.h>
 #include <wtf/CurrentTime.h>
 #include <wtf/DateMath.h>
-#include <wtf/Decoder.h>
-#include <wtf/Encoder.h>
 #include <wtf/text/CString.h>
 
 namespace WebCore {
 
-const uint32_t backForwardTreeEncodingVersion = 2;
-
 static long long generateSequenceNumber()
 {
     // Initialize to the current time to reduce the likelihood of generating
@@ -57,7 +53,7 @@ static void defaultNotifyHistoryItemChanged(HistoryItem*)
 {
 }
 
-void (*notifyHistoryItemChanged)(HistoryItem*) = defaultNotifyHistoryItemChanged;
+WEBCORE_EXPORT void (*notifyHistoryItemChanged)(HistoryItem*) = defaultNotifyHistoryItemChanged;
 
 HistoryItem::HistoryItem()
     : m_pageScaleFactor(0)
@@ -65,13 +61,7 @@ HistoryItem::HistoryItem()
     , m_isTargetItem(false)
     , m_itemSequenceNumber(generateSequenceNumber())
     , m_documentSequenceNumber(generateSequenceNumber())
-    , m_next(0)
-    , m_prev(0)
-#if PLATFORM(IOS)
-    , m_scale(0)
-    , m_scaleIsInitial(false)
-    , m_bookmarkID(0)
-#endif
+    , m_pruningReason(PruningReason::None)
 {
 }
 
@@ -84,14 +74,8 @@ HistoryItem::HistoryItem(const String& urlString, const String& title)
     , m_isTargetItem(false)
     , m_itemSequenceNumber(generateSequenceNumber())
     , m_documentSequenceNumber(generateSequenceNumber())
-    , m_next(0)
-    , m_prev(0)
-#if PLATFORM(IOS)
-    , m_scale(0)
-    , m_scaleIsInitial(false)
-    , m_bookmarkID(0)
-#endif
-{    
+    , m_pruningReason(PruningReason::None)
+{
     iconDatabase().retainIconForPageURL(m_urlString);
 }
 
@@ -105,39 +89,11 @@ HistoryItem::HistoryItem(const String& urlString, const String& title, const Str
     , m_isTargetItem(false)
     , m_itemSequenceNumber(generateSequenceNumber())
     , m_documentSequenceNumber(generateSequenceNumber())
-    , m_next(0)
-    , m_prev(0)
-#if PLATFORM(IOS)
-    , m_scale(0)
-    , m_scaleIsInitial(false)
-    , m_bookmarkID(0)
-#endif
+    , m_pruningReason(PruningReason::None)
 {
     iconDatabase().retainIconForPageURL(m_urlString);
 }
 
-HistoryItem::HistoryItem(const URL& url, const String& target, const String& parent, const String& title)
-    : m_urlString(url.string())
-    , m_originalURLString(url.string())
-    , m_target(target)
-    , m_parent(parent)
-    , m_title(title)
-    , m_pageScaleFactor(0)
-    , m_lastVisitWasFailure(false)
-    , m_isTargetItem(false)
-    , m_itemSequenceNumber(generateSequenceNumber())
-    , m_documentSequenceNumber(generateSequenceNumber())
-    , m_next(0)
-    , m_prev(0)
-#if PLATFORM(IOS)
-    , m_scale(0)
-    , m_scaleIsInitial(false)
-    , m_bookmarkID(0)
-#endif
-{    
-    iconDatabase().retainIconForPageURL(m_urlString);
-}
-
 HistoryItem::~HistoryItem()
 {
     ASSERT(!m_cachedPage);
@@ -150,21 +106,20 @@ inline HistoryItem::HistoryItem(const HistoryItem& item)
     , m_originalURLString(item.m_originalURLString)
     , m_referrer(item.m_referrer)
     , m_target(item.m_target)
-    , m_parent(item.m_parent)
     , m_title(item.m_title)
     , m_displayTitle(item.m_displayTitle)
-    , m_scrollPoint(item.m_scrollPoint)
+    , m_scrollPosition(item.m_scrollPosition)
     , m_pageScaleFactor(item.m_pageScaleFactor)
     , m_lastVisitWasFailure(item.m_lastVisitWasFailure)
     , m_isTargetItem(item.m_isTargetItem)
     , m_itemSequenceNumber(item.m_itemSequenceNumber)
     , m_documentSequenceNumber(item.m_documentSequenceNumber)
     , m_formContentType(item.m_formContentType)
+    , m_pruningReason(PruningReason::None)
 #if PLATFORM(IOS)
+    , m_obscuredInset(item.m_obscuredInset)
     , m_scale(item.m_scale)
     , m_scaleIsInitial(item.m_scaleIsInitial)
-    , m_bookmarkID(item.m_bookmarkID)
-    , m_sharedLinkUniqueIdentifier(item.m_sharedLinkUniqueIdentifier)
 #endif
 {
     if (item.m_formData)
@@ -174,14 +129,11 @@ inline HistoryItem::HistoryItem(const HistoryItem& item)
     m_children.reserveInitialCapacity(size);
     for (unsigned i = 0; i < size; ++i)
         m_children.uncheckedAppend(item.m_children[i]->copy());
-
-    if (item.m_redirectURLs)
-        m_redirectURLs = std::make_unique<Vector<String>>(*item.m_redirectURLs);
 }
 
-PassRefPtr<HistoryItem> HistoryItem::copy() const
+Ref<HistoryItem> HistoryItem::copy() const
 {
-    return adoptRef(new HistoryItem(*this));
+    return adoptRef(*new HistoryItem(*this));
 }
 
 void HistoryItem::reset()
@@ -192,21 +144,18 @@ void HistoryItem::reset()
     m_originalURLString = String();
     m_referrer = String();
     m_target = String();
-    m_parent = String();
     m_title = String();
     m_displayTitle = String();
 
     m_lastVisitWasFailure = false;
     m_isTargetItem = false;
 
-    m_redirectURLs = nullptr;
-
     m_itemSequenceNumber = generateSequenceNumber();
 
-    m_stateObject = 0;
+    m_stateObject = nullptr;
     m_documentSequenceNumber = generateSequenceNumber();
 
-    m_formData = 0;
+    m_formData = nullptr;
     m_formContentType = String();
 
     clearChildren();
@@ -259,11 +208,6 @@ const String& HistoryItem::target() const
     return m_target;
 }
 
-const String& HistoryItem::parent() const
-{
-    return m_parent;
-}
-
 void HistoryItem::setAlternateTitle(const String& alternateTitle)
 {
     m_displayTitle = alternateTitle;
@@ -283,7 +227,7 @@ void HistoryItem::setURLString(const String& urlString)
 
 void HistoryItem::setURL(const URL& url)
 {
-    pageCache()->remove(this);
+    PageCache::singleton().remove(*this);
     setURLString(url.string());
     clearDocumentState();
 }
@@ -312,25 +256,19 @@ void HistoryItem::setTarget(const String& target)
     notifyHistoryItemChanged(this);
 }
 
-void HistoryItem::setParent(const String& parent)
-{
-    m_parent = parent;
-}
-
-const IntPoint& HistoryItem::scrollPoint() const
+const IntPoint& HistoryItem::scrollPosition() const
 {
-    return m_scrollPoint;
+    return m_scrollPosition;
 }
 
-void HistoryItem::setScrollPoint(const IntPoint& point)
+void HistoryItem::setScrollPosition(const IntPoint& position)
 {
-    m_scrollPoint = point;
+    m_scrollPosition = position;
 }
 
-void HistoryItem::clearScrollPoint()
+void HistoryItem::clearScrollPosition()
 {
-    m_scrollPoint.setX(0);
-    m_scrollPoint.setY(0);
+    m_scrollPosition = IntPoint();
 }
 
 float HistoryItem::pageScaleFactor() const
@@ -358,6 +296,16 @@ void HistoryItem::clearDocumentState()
     m_documentState.clear();
 }
 
+void HistoryItem::setShouldOpenExternalURLsPolicy(ShouldOpenExternalURLsPolicy policy)
+{
+    m_shouldOpenExternalURLsPolicy = policy;
+}
+
+ShouldOpenExternalURLsPolicy HistoryItem::shouldOpenExternalURLsPolicy() const
+{
+    return m_shouldOpenExternalURLsPolicy;
+}
+
 bool HistoryItem::isTargetItem() const
 {
     return m_isTargetItem;
@@ -368,71 +316,52 @@ void HistoryItem::setIsTargetItem(bool flag)
     m_isTargetItem = flag;
 }
 
-void HistoryItem::setStateObject(PassRefPtr<SerializedScriptValue> object)
+void HistoryItem::setStateObject(RefPtr<SerializedScriptValue>&& object)
 {
-    m_stateObject = object;
+    m_stateObject = WTFMove(object);
 }
 
-void HistoryItem::addChildItem(PassRefPtr<HistoryItem> child)
+void HistoryItem::addChildItem(Ref<HistoryItem>&& child)
 {
     ASSERT(!childItemWithTarget(child->target()));
-    m_children.append(child);
+    m_children.append(WTFMove(child));
 }
 
-void HistoryItem::setChildItem(PassRefPtr<HistoryItem> child)
+void HistoryItem::setChildItem(Ref<HistoryItem>&& child)
 {
     ASSERT(!child->isTargetItem());
     unsigned size = m_children.size();
     for (unsigned i = 0; i < size; ++i)  {
         if (m_children[i]->target() == child->target()) {
             child->setIsTargetItem(m_children[i]->isTargetItem());
-            m_children[i] = child;
+            m_children[i] = WTFMove(child);
             return;
         }
     }
-    m_children.append(child);
+    m_children.append(WTFMove(child));
 }
 
-HistoryItem* HistoryItem::childItemWithTarget(const String& target) const
+HistoryItem* HistoryItem::childItemWithTarget(const String& target)
 {
     unsigned size = m_children.size();
     for (unsigned i = 0; i < size; ++i) {
         if (m_children[i]->target() == target)
-            return m_children[i].get();
+            return m_children[i].ptr();
     }
-    return 0;
+    return nullptr;
 }
 
-HistoryItem* HistoryItem::childItemWithDocumentSequenceNumber(long long number) const
+HistoryItem* HistoryItem::childItemWithDocumentSequenceNumber(long long number)
 {
     unsigned size = m_children.size();
     for (unsigned i = 0; i < size; ++i) {
         if (m_children[i]->documentSequenceNumber() == number)
-            return m_children[i].get();
+            return m_children[i].ptr();
     }
-    return 0;
-}
-
-// <rdar://problem/4895849> HistoryItem::findTargetItem() should be replaced with a non-recursive method.
-HistoryItem* HistoryItem::findTargetItem()
-{
-    if (m_isTargetItem)
-        return this;
-    unsigned size = m_children.size();
-    for (unsigned i = 0; i < size; ++i) {
-        if (HistoryItem* match = m_children[i]->targetItem())
-            return match;
-    }
-    return 0;
-}
-
-HistoryItem* HistoryItem::targetItem()
-{
-    HistoryItem* foundItem = findTargetItem();
-    return foundItem ? foundItem : this;
+    return nullptr;
 }
 
-const HistoryItemVector& HistoryItem::children() const
+const Vector<Ref<HistoryItem>>& HistoryItem::children() const
 {
     return m_children;
 }
@@ -447,49 +376,37 @@ void HistoryItem::clearChildren()
     m_children.clear();
 }
 
-bool HistoryItem::isAncestorOf(const HistoryItem* item) const
-{
-    for (size_t i = 0; i < m_children.size(); ++i) {
-        HistoryItem* child = m_children[i].get();
-        if (child == item)
-            return true;
-        if (child->isAncestorOf(item))
-            return true;
-    }
-    return false;
-}
-
 // We do same-document navigation if going to a different item and if either of the following is true:
 // - The other item corresponds to the same document (for history entries created via pushState or fragment changes).
 // - The other item corresponds to the same set of documents, including frames (for history entries created via regular navigation)
-bool HistoryItem::shouldDoSameDocumentNavigationTo(HistoryItem* otherItem) const
+bool HistoryItem::shouldDoSameDocumentNavigationTo(HistoryItem& otherItem) const
 {
-    if (this == otherItem)
+    if (this == &otherItem)
         return false;
 
-    if (stateObject() || otherItem->stateObject())
-        return documentSequenceNumber() == otherItem->documentSequenceNumber();
+    if (stateObject() || otherItem.stateObject())
+        return documentSequenceNumber() == otherItem.documentSequenceNumber();
     
-    if ((url().hasFragmentIdentifier() || otherItem->url().hasFragmentIdentifier()) && equalIgnoringFragmentIdentifier(url(), otherItem->url()))
-        return documentSequenceNumber() == otherItem->documentSequenceNumber();        
+    if ((url().hasFragmentIdentifier() || otherItem.url().hasFragmentIdentifier()) && equalIgnoringFragmentIdentifier(url(), otherItem.url()))
+        return documentSequenceNumber() == otherItem.documentSequenceNumber();
     
     return hasSameDocumentTree(otherItem);
 }
 
 // Does a recursive check that this item and its descendants have the same
 // document sequence numbers as the other item.
-bool HistoryItem::hasSameDocumentTree(HistoryItem* otherItem) const
+bool HistoryItem::hasSameDocumentTree(HistoryItem& otherItem) const
 {
-    if (documentSequenceNumber() != otherItem->documentSequenceNumber())
+    if (documentSequenceNumber() != otherItem.documentSequenceNumber())
         return false;
         
-    if (children().size() != otherItem->children().size())
+    if (children().size() != otherItem.children().size())
         return false;
 
     for (size_t i = 0; i < children().size(); i++) {
-        HistoryItem* child = children()[i].get();
-        HistoryItem* otherChild = otherItem->childItemWithDocumentSequenceNumber(child->documentSequenceNumber());
-        if (!otherChild || !child->hasSameDocumentTree(otherChild))
+        auto& child = children()[i].get();
+        auto* otherChild = otherItem.childItemWithDocumentSequenceNumber(child.documentSequenceNumber());
+        if (!otherChild || !child.hasSameDocumentTree(*otherChild))
             return false;
     }
 
@@ -498,16 +415,16 @@ bool HistoryItem::hasSameDocumentTree(HistoryItem* otherItem) const
 
 // Does a non-recursive check that this item and its immediate children have the
 // same frames as the other item.
-bool HistoryItem::hasSameFrames(HistoryItem* otherItem) const
+bool HistoryItem::hasSameFrames(HistoryItem& otherItem) const
 {
-    if (target() != otherItem->target())
+    if (target() != otherItem.target())
         return false;
         
-    if (children().size() != otherItem->children().size())
+    if (children().size() != otherItem.children().size())
         return false;
 
     for (size_t i = 0; i < children().size(); i++) {
-        if (!otherItem->childItemWithTarget(children()[i]->target()))
+        if (!otherItem.childItemWithTarget(children()[i]->target()))
             return false;
     }
 
@@ -523,20 +440,20 @@ void HistoryItem::setFormInfoFromRequest(const ResourceRequest& request)
 {
     m_referrer = request.httpReferrer();
     
-    if (equalIgnoringCase(request.httpMethod(), "POST")) {
+    if (equalLettersIgnoringASCIICase(request.httpMethod(), "post")) {
         // FIXME: Eventually we have to make this smart enough to handle the case where
         // we have a stream for the body to handle the "data interspersed with files" feature.
         m_formData = request.httpBody();
         m_formContentType = request.httpContentType();
     } else {
-        m_formData = 0;
+        m_formData = nullptr;
         m_formContentType = String();
     }
 }
 
-void HistoryItem::setFormData(PassRefPtr<FormData> formData)
+void HistoryItem::setFormData(RefPtr<FormData>&& formData)
 {
-    m_formData = formData;
+    m_formData = WTFMove(formData);
 }
 
 void HistoryItem::setFormContentType(const String& formContentType)
@@ -549,266 +466,15 @@ FormData* HistoryItem::formData()
     return m_formData.get();
 }
 
-bool HistoryItem::isCurrentDocument(Document* doc) const
+bool HistoryItem::isCurrentDocument(Document& document) const
 {
     // FIXME: We should find a better way to check if this is the current document.
-    return equalIgnoringFragmentIdentifier(url(), doc->url());
-}
-
-void HistoryItem::addRedirectURL(const String& url)
-{
-    if (!m_redirectURLs)
-        m_redirectURLs = std::make_unique<Vector<String>>();
-
-    // Our API allows us to store all the URLs in the redirect chain, but for
-    // now we only have a use for the final URL.
-    (*m_redirectURLs).resize(1);
-    (*m_redirectURLs)[0] = url;
-}
-
-Vector<String>* HistoryItem::redirectURLs() const
-{
-    return m_redirectURLs.get();
-}
-
-void HistoryItem::setRedirectURLs(std::unique_ptr<Vector<String>> redirectURLs)
-{
-    m_redirectURLs = std::move(redirectURLs);
-}
-
-void HistoryItem::encodeBackForwardTree(Encoder& encoder) const
-{
-    encoder.encodeUInt32(backForwardTreeEncodingVersion);
-
-    encodeBackForwardTreeNode(encoder);
-}
-
-void HistoryItem::encodeBackForwardTree(KeyedEncoder& encoder) const
-{
-    encoder.encodeUInt32("version", backForwardTreeEncodingVersion);
-
-    encoder.encodeObject("root", *this, [](KeyedEncoder& encoder, const HistoryItem& item) {
-        item.encodeBackForwardTreeNode(encoder);
-    });
+    return equalIgnoringFragmentIdentifier(url(), document.url());
 }
 
-void HistoryItem::encodeBackForwardTreeNode(Encoder& encoder) const
+void HistoryItem::notifyChanged()
 {
-    size_t size = m_children.size();
-    encoder.encodeUInt64(size);
-    for (size_t i = 0; i < size; ++i) {
-        const HistoryItem& child = *m_children[i];
-
-        encoder.encodeString(child.m_originalURLString);
-
-        encoder.encodeString(child.m_urlString);
-
-        child.encodeBackForwardTreeNode(encoder);
-    }
-
-    encoder.encodeInt64(m_documentSequenceNumber);
-
-    size = m_documentState.size();
-    encoder.encodeUInt64(size);
-    for (size_t i = 0; i < size; ++i)
-        encoder.encodeString(m_documentState[i]);
-
-    encoder.encodeString(m_formContentType);
-
-    encoder.encodeBool(m_formData);
-    if (m_formData)
-        m_formData->encode(encoder);
-
-    encoder.encodeInt64(m_itemSequenceNumber);
-
-    encoder.encodeString(m_referrer);
-
-    encoder.encodeInt32(m_scrollPoint.x());
-    encoder.encodeInt32(m_scrollPoint.y());
-    
-    encoder.encodeFloat(m_pageScaleFactor);
-
-    encoder.encodeBool(m_stateObject);
-    if (m_stateObject)
-        encoder.encodeBytes(m_stateObject->data().data(), m_stateObject->data().size());
-
-    encoder.encodeString(m_target);
-}
-
-void HistoryItem::encodeBackForwardTreeNode(KeyedEncoder& encoder) const
-{
-    encoder.encodeObjects("children", m_children.begin(), m_children.end(), [](KeyedEncoder& encoder, const RefPtr<HistoryItem>& child) {
-        encoder.encodeString("originalURLString", child->m_originalURLString);
-        encoder.encodeString("urlString", child->m_urlString);
-
-        child->encodeBackForwardTreeNode(encoder);
-    });
-
-    encoder.encodeInt64("documentSequenceNumber", m_documentSequenceNumber);
-
-    encoder.encodeObjects("documentState", m_documentState.begin(), m_documentState.end(), [](KeyedEncoder& encoder, const String& string) {
-        encoder.encodeString("string", string);
-    });
-
-    encoder.encodeString("formContentType", m_formContentType);
-
-    encoder.encodeConditionalObject("formData", m_formData.get(), [](KeyedEncoder&, const FormData&) {
-        // FIXME: Implement.
-    });
-
-    encoder.encodeInt64("itemSequenceNumber", m_itemSequenceNumber);
-
-    encoder.encodeString("referrer", m_referrer);
-
-    encoder.encodeObject("scrollPoint", m_scrollPoint, [](KeyedEncoder& encoder, const IntPoint& scrollPoint) {
-        encoder.encodeInt32("x", scrollPoint.x());
-        encoder.encodeInt32("y", scrollPoint.y());
-    });
-
-    encoder.encodeFloat("pageScaleFactor", m_pageScaleFactor);
-
-    encoder.encodeConditionalObject("stateObject", m_stateObject.get(), [](KeyedEncoder& encoder, const SerializedScriptValue& stateObject) {
-        encoder.encodeBytes("data", stateObject.data().data(), stateObject.data().size());
-    });
-
-    encoder.encodeString("target", m_target);
-}
-
-struct DecodeRecursionStackElement {
-    RefPtr<HistoryItem> node;
-    size_t i;
-    uint64_t size;
-
-    DecodeRecursionStackElement(PassRefPtr<HistoryItem> node, size_t i, uint64_t size)
-        : node(node)
-        , i(i)
-        , size(size)
-    {
-    }
-};
-
-PassRefPtr<HistoryItem> HistoryItem::decodeBackForwardTree(const String& topURLString, const String& topTitle, const String& topOriginalURLString, Decoder& decoder)
-{
-    // Since the data stream is not trusted, the decode has to be non-recursive.
-    // We don't want bad data to cause a stack overflow.
-
-    uint32_t version;
-    if (!decoder.decodeUInt32(version))
-        return 0;
-    if (version != backForwardTreeEncodingVersion)
-        return 0;
-
-    String urlString = topURLString;
-    String title = topTitle;
-    String originalURLString = topOriginalURLString;
-
-    Vector<DecodeRecursionStackElement, 16> recursionStack;
-
-recurse:
-    RefPtr<HistoryItem> node = create(urlString, title);
-
-    node->setOriginalURLString(originalURLString);
-
-    title = String();
-
-    uint64_t size;
-    if (!decoder.decodeUInt64(size))
-        return 0;
-    size_t i;
-    RefPtr<HistoryItem> child;
-    for (i = 0; i < size; ++i) {
-        if (!decoder.decodeString(originalURLString))
-            return 0;
-
-        if (!decoder.decodeString(urlString))
-            return 0;
-
-        recursionStack.append(DecodeRecursionStackElement(node.release(), i, size));
-        goto recurse;
-
-resume:
-        node->m_children.append(child.release());
-    }
-
-    if (!decoder.decodeInt64(node->m_documentSequenceNumber))
-        return 0;
-
-    if (!decoder.decodeUInt64(size))
-        return 0;
-    for (i = 0; i < size; ++i) {
-        String state;
-        if (!decoder.decodeString(state))
-            return 0;
-        node->m_documentState.append(state);
-    }
-
-    if (!decoder.decodeString(node->m_formContentType))
-        return 0;
-
-    bool hasFormData;
-    if (!decoder.decodeBool(hasFormData))
-        return 0;
-    if (hasFormData) {
-        node->m_formData = FormData::decode(decoder);
-        if (!node->m_formData)
-            return 0;
-    }
-
-    if (!decoder.decodeInt64(node->m_itemSequenceNumber))
-        return 0;
-
-    if (!decoder.decodeString(node->m_referrer))
-        return 0;
-
-    int32_t x;
-    if (!decoder.decodeInt32(x))
-        return 0;
-    int32_t y;
-    if (!decoder.decodeInt32(y))
-        return 0;
-    node->m_scrollPoint = IntPoint(x, y);
-    
-    if (!decoder.decodeFloat(node->m_pageScaleFactor))
-        return 0;
-
-    bool hasStateObject;
-    if (!decoder.decodeBool(hasStateObject))
-        return 0;
-    if (hasStateObject) {
-        Vector<uint8_t> bytes;
-        if (!decoder.decodeBytes(bytes))
-            return 0;
-        node->m_stateObject = SerializedScriptValue::adopt(bytes);
-    }
-
-    if (!decoder.decodeString(node->m_target))
-        return 0;
-
-    // Simulate recursion with our own stack.
-    if (!recursionStack.isEmpty()) {
-        DecodeRecursionStackElement& element = recursionStack.last();
-        child = node.release();
-        node = element.node.release();
-        i = element.i;
-        size = element.size;
-        recursionStack.removeLast();
-        goto resume;
-    }
-
-    return node.release();
-}
-
-PassRefPtr<HistoryItem> HistoryItem::decodeBackForwardTree(const String&, const String&, const String&, KeyedDecoder& decoder)
-{
-    uint32_t version;
-    if (!decoder.decodeUInt32("version", version))
-        return nullptr;
-    
-    if (version != backForwardTreeEncodingVersion)
-        return nullptr;
-
-    // FIXME: Implement.
-    return nullptr;
+    notifyHistoryItemChanged(this);
 }
 
 #ifndef NDEBUG
diff --git a/Source/WebCore/history/HistoryItem.h b/Source/WebCore/history/HistoryItem.h
index 9ae72afa0..60b0b8c5a 100644
--- a/Source/WebCore/history/HistoryItem.h
+++ b/Source/WebCore/history/HistoryItem.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006, 2008, 2011 Apple Inc. All rights reserved.
+ * Copyright (C) 2006, 2008, 2011, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Research In Motion Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -11,10 +11,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -24,10 +24,12 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
-#ifndef HistoryItem_h
-#define HistoryItem_h
+#pragma once
 
+#include "FloatRect.h"
+#include "FrameLoaderTypes.h"
 #include "IntPoint.h"
+#include "IntRect.h"
 #include "SerializedScriptValue.h"
 #include <memory>
 #include <wtf/RefCounted.h>
@@ -37,7 +39,7 @@
 #include "ViewportArguments.h"
 #endif
 
-#if PLATFORM(MAC)
+#if PLATFORM(COCOA)
 #import <wtf/RetainPtr.h>
 typedef struct objc_object* id;
 #endif
@@ -49,89 +51,78 @@ class Document;
 class FormData;
 class HistoryItem;
 class Image;
-class KeyedDecoder;
-class KeyedEncoder;
 class ResourceRequest;
 class URL;
+enum class PruningReason;
 
-typedef Vector<RefPtr<HistoryItem>> HistoryItemVector;
-
-extern void (*notifyHistoryItemChanged)(HistoryItem*);
+WEBCORE_EXPORT extern void (*notifyHistoryItemChanged)(HistoryItem*);
 
 class HistoryItem : public RefCounted<HistoryItem> {
     friend class PageCache;
 
 public: 
-    static PassRefPtr<HistoryItem> create() { return adoptRef(new HistoryItem); }
-    static PassRefPtr<HistoryItem> create(const String& urlString, const String& title)
-    {
-        return adoptRef(new HistoryItem(urlString, title));
-    }
-    static PassRefPtr<HistoryItem> create(const String& urlString, const String& title, const String& alternateTitle)
+    static Ref<HistoryItem> create() { return adoptRef(*new HistoryItem); }
+    static Ref<HistoryItem> create(const String& urlString, const String& title)
     {
-        return adoptRef(new HistoryItem(urlString, title, alternateTitle));
+        return adoptRef(*new HistoryItem(urlString, title));
     }
-    static PassRefPtr<HistoryItem> create(const URL& url, const String& target, const String& parent, const String& title)
+    static Ref<HistoryItem> create(const String& urlString, const String& title, const String& alternateTitle)
     {
-        return adoptRef(new HistoryItem(url, target, parent, title));
+        return adoptRef(*new HistoryItem(urlString, title, alternateTitle));
     }
     
-    ~HistoryItem();
+    WEBCORE_EXPORT ~HistoryItem();
 
-    PassRefPtr<HistoryItem> copy() const;
+    WEBCORE_EXPORT Ref<HistoryItem> copy() const;
 
     // Resets the HistoryItem to its initial state, as returned by create().
     void reset();
     
-    void encodeBackForwardTree(Encoder&) const;
-    void encodeBackForwardTree(KeyedEncoder&) const;
-    static PassRefPtr<HistoryItem> decodeBackForwardTree(const String& urlString, const String& title, const String& originalURLString, Decoder&);
-    static PassRefPtr<HistoryItem> decodeBackForwardTree(const String& urlString, const String& title, const String& originalURLString, KeyedDecoder&);
-
-    const String& originalURLString() const;
-    const String& urlString() const;
-    const String& title() const;
+    WEBCORE_EXPORT const String& originalURLString() const;
+    WEBCORE_EXPORT const String& urlString() const;
+    WEBCORE_EXPORT const String& title() const;
     
     bool isInPageCache() const { return m_cachedPage.get(); }
-    bool hasCachedPageExpired() const;
+    WEBCORE_EXPORT bool hasCachedPageExpired() const;
 
-    void setAlternateTitle(const String& alternateTitle);
-    const String& alternateTitle() const;
+    WEBCORE_EXPORT void setAlternateTitle(const String&);
+    WEBCORE_EXPORT const String& alternateTitle() const;
     
-    const String& parent() const;
-    URL url() const;
-    URL originalURL() const;
-    const String& referrer() const;
-    const String& target() const;
-    bool isTargetItem() const;
+    WEBCORE_EXPORT URL url() const;
+    WEBCORE_EXPORT URL originalURL() const;
+    WEBCORE_EXPORT const String& referrer() const;
+    WEBCORE_EXPORT const String& target() const;
+    WEBCORE_EXPORT bool isTargetItem() const;
     
-    FormData* formData();
-    String formContentType() const;
+    WEBCORE_EXPORT FormData* formData();
+    WEBCORE_EXPORT String formContentType() const;
     
     bool lastVisitWasFailure() const { return m_lastVisitWasFailure; }
 
-    const IntPoint& scrollPoint() const;
-    void setScrollPoint(const IntPoint&);
-    void clearScrollPoint();
+    WEBCORE_EXPORT const IntPoint& scrollPosition() const;
+    WEBCORE_EXPORT void setScrollPosition(const IntPoint&);
+    void clearScrollPosition();
     
-    float pageScaleFactor() const;
-    void setPageScaleFactor(float);
+    WEBCORE_EXPORT float pageScaleFactor() const;
+    WEBCORE_EXPORT void setPageScaleFactor(float);
     
-    const Vector<String>& documentState() const;
-    void setDocumentState(const Vector<String>&);
+    WEBCORE_EXPORT const Vector<String>& documentState() const;
+    WEBCORE_EXPORT void setDocumentState(const Vector<String>&);
     void clearDocumentState();
 
+    WEBCORE_EXPORT void setShouldOpenExternalURLsPolicy(ShouldOpenExternalURLsPolicy);
+    WEBCORE_EXPORT ShouldOpenExternalURLsPolicy shouldOpenExternalURLsPolicy() const;
+
     void setURL(const URL&);
-    void setURLString(const String&);
-    void setOriginalURLString(const String&);
-    void setReferrer(const String&);
-    void setTarget(const String&);
-    void setParent(const String&);
-    void setTitle(const String&);
-    void setIsTargetItem(bool);
+    WEBCORE_EXPORT void setURLString(const String&);
+    WEBCORE_EXPORT void setOriginalURLString(const String&);
+    WEBCORE_EXPORT void setReferrer(const String&);
+    WEBCORE_EXPORT void setTarget(const String&);
+    WEBCORE_EXPORT void setTitle(const String&);
+    WEBCORE_EXPORT void setIsTargetItem(bool);
     
-    void setStateObject(PassRefPtr<SerializedScriptValue> object);
-    PassRefPtr<SerializedScriptValue> stateObject() const { return m_stateObject; }
+    WEBCORE_EXPORT void setStateObject(RefPtr<SerializedScriptValue>&&);
+    SerializedScriptValue* stateObject() const { return m_stateObject.get(); }
 
     void setItemSequenceNumber(long long number) { m_itemSequenceNumber = number; }
     long long itemSequenceNumber() const { return m_itemSequenceNumber; }
@@ -140,38 +131,32 @@ public:
     long long documentSequenceNumber() const { return m_documentSequenceNumber; }
 
     void setFormInfoFromRequest(const ResourceRequest&);
-    void setFormData(PassRefPtr<FormData>);
-    void setFormContentType(const String&);
+    WEBCORE_EXPORT void setFormData(RefPtr<FormData>&&);
+    WEBCORE_EXPORT void setFormContentType(const String&);
 
     void setLastVisitWasFailure(bool wasFailure) { m_lastVisitWasFailure = wasFailure; }
 
-    void addChildItem(PassRefPtr<HistoryItem>);
-    void setChildItem(PassRefPtr<HistoryItem>);
-    HistoryItem* childItemWithTarget(const String&) const;
-    HistoryItem* childItemWithDocumentSequenceNumber(long long number) const;
-    HistoryItem* targetItem();
-    const HistoryItemVector& children() const;
-    bool hasChildren() const;
+    WEBCORE_EXPORT void addChildItem(Ref<HistoryItem>&&);
+    void setChildItem(Ref<HistoryItem>&&);
+    WEBCORE_EXPORT HistoryItem* childItemWithTarget(const String&);
+    HistoryItem* childItemWithDocumentSequenceNumber(long long number);
+    WEBCORE_EXPORT const Vector<Ref<HistoryItem>>& children() const;
+    WEBCORE_EXPORT bool hasChildren() const;
     void clearChildren();
-    bool isAncestorOf(const HistoryItem*) const;
     
-    bool shouldDoSameDocumentNavigationTo(HistoryItem* otherItem) const;
-    bool hasSameFrames(HistoryItem* otherItem) const;
-
-    void addRedirectURL(const String&);
-    Vector<String>* redirectURLs() const;
-    void setRedirectURLs(std::unique_ptr<Vector<String>>);
+    bool shouldDoSameDocumentNavigationTo(HistoryItem& otherItem) const;
+    bool hasSameFrames(HistoryItem& otherItem) const;
 
-    bool isCurrentDocument(Document*) const;
+    bool isCurrentDocument(Document&) const;
     
-#if PLATFORM(MAC)
-    id viewState() const;
-    void setViewState(id);
+#if PLATFORM(COCOA)
+    WEBCORE_EXPORT id viewState() const;
+    WEBCORE_EXPORT void setViewState(id);
     
     // Transient properties may be of any ObjC type.  They are intended to be used to store state per back/forward list entry.
     // The properties will not be persisted; when the history item is removed, the properties will be lost.
-    id getTransientProperty(const String&) const;
-    void setTransientProperty(const String&, id);
+    WEBCORE_EXPORT id getTransientProperty(const String&) const;
+    WEBCORE_EXPORT void setTransientProperty(const String&, id);
 #endif
 
 #ifndef NDEBUG
@@ -180,8 +165,24 @@ public:
 #endif
 
 #if PLATFORM(IOS)
+    FloatRect exposedContentRect() const { return m_exposedContentRect; }
+    void setExposedContentRect(FloatRect exposedContentRect) { m_exposedContentRect = exposedContentRect; }
+
+    IntRect unobscuredContentRect() const { return m_unobscuredContentRect; }
+    void setUnobscuredContentRect(IntRect unobscuredContentRect) { m_unobscuredContentRect = unobscuredContentRect; }
+
+    FloatSize obscuredInset() const { return m_obscuredInset; }
+    void setObscuredInset(const FloatSize& inset) { m_obscuredInset = inset; }
+
+    FloatSize minimumLayoutSizeInScrollViewCoordinates() const { return m_minimumLayoutSizeInScrollViewCoordinates; }
+    void setMinimumLayoutSizeInScrollViewCoordinates(FloatSize minimumLayoutSizeInScrollViewCoordinates) { m_minimumLayoutSizeInScrollViewCoordinates = minimumLayoutSizeInScrollViewCoordinates; }
+
+    IntSize contentSize() const { return m_contentSize; }
+    void setContentSize(IntSize contentSize) { m_contentSize = contentSize; }
+
     float scale() const { return m_scale; }
     bool scaleIsInitial() const { return m_scaleIsInitial; }
+    void setScaleIsInitial(bool scaleIsInitial) { m_scaleIsInitial = scaleIsInitial; }
     void setScale(float newScale, bool isInitial)
     {
         m_scale = newScale;
@@ -190,46 +191,40 @@ public:
 
     const ViewportArguments& viewportArguments() const { return m_viewportArguments; }
     void setViewportArguments(const ViewportArguments& viewportArguments) { m_viewportArguments = viewportArguments; }
-
-    uint32_t bookmarkID() const { return m_bookmarkID; }
-    void setBookmarkID(uint32_t bookmarkID) { m_bookmarkID = bookmarkID; }
-    String sharedLinkUniqueIdentifier() const { return m_sharedLinkUniqueIdentifier; }
-    void setSharedLinkUniqueIdentifier(const String& sharedLinkUniqueidentifier) { m_sharedLinkUniqueIdentifier = sharedLinkUniqueidentifier; }
 #endif
 
-private:
-    HistoryItem();
-    HistoryItem(const String& urlString, const String& title);
-    HistoryItem(const String& urlString, const String& title, const String& alternateTitle);
-    HistoryItem(const URL& url, const String& frameName, const String& parent, const String& title);
+    void notifyChanged();
 
-    explicit HistoryItem(const HistoryItem&);
+    void setWasRestoredFromSession(bool wasRestoredFromSession) { m_wasRestoredFromSession = wasRestoredFromSession; }
+    bool wasRestoredFromSession() const { return m_wasRestoredFromSession; }
 
-    bool hasSameDocumentTree(HistoryItem* otherItem) const;
+private:
+    WEBCORE_EXPORT HistoryItem();
+    WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title);
+    WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title, const String& alternateTitle);
 
-    HistoryItem* findTargetItem();
+    HistoryItem(const HistoryItem&);
 
-    void encodeBackForwardTreeNode(Encoder&) const;
-    void encodeBackForwardTreeNode(KeyedEncoder&) const;
+    bool hasSameDocumentTree(HistoryItem& otherItem) const;
 
     String m_urlString;
     String m_originalURLString;
     String m_referrer;
     String m_target;
-    String m_parent;
     String m_title;
     String m_displayTitle;
     
-    IntPoint m_scrollPoint;
+    IntPoint m_scrollPosition;
     float m_pageScaleFactor;
     Vector<String> m_documentState;
+
+    ShouldOpenExternalURLsPolicy m_shouldOpenExternalURLsPolicy { ShouldOpenExternalURLsPolicy::ShouldNotAllow };
     
-    HistoryItemVector m_children;
+    Vector<Ref<HistoryItem>> m_children;
     
     bool m_lastVisitWasFailure;
     bool m_isTargetItem;
-
-    std::unique_ptr<Vector<String>> m_redirectURLs;
+    bool m_wasRestoredFromSession { false };
 
     // If two HistoryItems have the same item sequence number, then they are
     // clones of one another.  Traversing history from one such HistoryItem to
@@ -250,30 +245,29 @@ private:
     String m_formContentType;
 
     // PageCache controls these fields.
-    HistoryItem* m_next;
-    HistoryItem* m_prev;
     std::unique_ptr<CachedPage> m_cachedPage;
+    PruningReason m_pruningReason;
 
 #if PLATFORM(IOS)
-    float m_scale;
-    bool m_scaleIsInitial;
+    FloatRect m_exposedContentRect;
+    IntRect m_unobscuredContentRect;
+    FloatSize m_minimumLayoutSizeInScrollViewCoordinates;
+    IntSize m_contentSize;
+    FloatSize m_obscuredInset;
+    float m_scale { 0 }; // Note that UIWebView looks for a non-zero value, so this has to start as 0.
+    bool m_scaleIsInitial { false };
     ViewportArguments m_viewportArguments;
-
-    uint32_t m_bookmarkID;
-    String m_sharedLinkUniqueIdentifier;
 #endif
 
-#if PLATFORM(MAC)
+#if PLATFORM(COCOA)
     RetainPtr<id> m_viewState;
     std::unique_ptr<HashMap<String, RetainPtr<id>>> m_transientProperties;
 #endif
-}; //class HistoryItem
+};
 
-} //namespace WebCore
+} // namespace WebCore
 
-#ifndef NDEBUG
-// Outside the WebCore namespace for ease of invocation from gdb.
+#if ENABLE(TREE_DEBUGGING)
+// Outside the WebCore namespace for ease of invocation from the debugger.
 extern "C" int showTree(const WebCore::HistoryItem*);
 #endif
-
-#endif // HISTORYITEM_H
diff --git a/Source/WebCore/history/PageCache.cpp b/Source/WebCore/history/PageCache.cpp
index 57ec24efb..02f8ff418 100644
--- a/Source/WebCore/history/PageCache.cpp
+++ b/Source/WebCore/history/PageCache.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 Apple Inc.  All rights reserved.
+ * Copyright (C) 2007, 2014, 2015 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -28,28 +28,29 @@
 
 #include "ApplicationCacheHost.h"
 #include "BackForwardController.h"
-#include "MemoryCache.h"
 #include "CachedPage.h"
 #include "DOMWindow.h"
-#include "DatabaseManager.h"
 #include "DeviceMotionController.h"
 #include "DeviceOrientationController.h"
+#include "DiagnosticLoggingClient.h"
+#include "DiagnosticLoggingKeys.h"
 #include "Document.h"
 #include "DocumentLoader.h"
+#include "FocusController.h"
 #include "FrameLoader.h"
 #include "FrameLoaderClient.h"
-#include "FrameLoaderStateMachine.h"
 #include "FrameView.h"
-#include "HistogramSupport.h"
 #include "HistoryController.h"
-#include "HistoryItem.h"
+#include "IgnoreOpensDuringUnloadCountIncrementer.h"
 #include "Logging.h"
 #include "MainFrame.h"
+#include "MemoryPressureHandler.h"
+#include "NoEventDispatchAssertion.h"
 #include "Page.h"
 #include "Settings.h"
-#include "SharedWorkerRepository.h"
 #include "SubframeLoader.h"
-#include <wtf/CurrentTime.h>
+#include <wtf/NeverDestroyed.h>
+#include <wtf/SetForScope.h>
 #include <wtf/text/CString.h>
 #include <wtf/text/StringConcatenate.h>
 
@@ -57,514 +58,448 @@
 #include "DeviceProximityController.h"
 #endif
 
-#if PLATFORM(IOS)
-#include "MemoryPressureHandler.h"
-#endif
-
 namespace WebCore {
 
-#if !defined(NDEBUG)
-
 #define PCLOG(...) LOG(PageCache, "%*s%s", indentLevel*4, "", makeString(__VA_ARGS__).utf8().data())
-    
-// Used in histograms, please only add at the end, and do not remove elements (renaming e.g. to "FooEnumUnused1" is fine).
-// This is because statistics may be gathered from histograms between versions over time, and re-using values causes collisions.
-enum ReasonFrameCannotBeInPageCache {
-    NoDocumentLoader = 0,
-    MainDocumentError,
-    IsErrorPage,
-    HasPlugins,
-    IsHttpsAndCacheControlled,
-    HasUnloadListener,
-    HasDatabaseHandles,
-    HasSharedWorkers,
-    NoHistoryItem,
-    QuickRedirectComing,
-    IsLoadingInAPISense,
-    IsStopping,
-    CannotSuspendActiveDOMObjects,
-    DocumentLoaderUsesApplicationCache,
-    ClientDeniesCaching,
-    NumberOfReasonsFramesCannotBeInPageCache,
-};
-COMPILE_ASSERT(NumberOfReasonsFramesCannotBeInPageCache <= sizeof(unsigned)*8, ReasonFrameCannotBeInPageCacheDoesNotFitInBitmap);
-
-static unsigned logCanCacheFrameDecision(Frame* frame, int indentLevel)
+
+static inline void logPageCacheFailureDiagnosticMessage(DiagnosticLoggingClient& client, const String& reason)
+{
+    client.logDiagnosticMessage(DiagnosticLoggingKeys::pageCacheFailureKey(), reason, ShouldSample::Yes);
+}
+
+static inline void logPageCacheFailureDiagnosticMessage(Page* page, const String& reason)
+{
+    if (!page)
+        return;
+
+    logPageCacheFailureDiagnosticMessage(page->diagnosticLoggingClient(), reason);
+}
+
+static bool canCacheFrame(Frame& frame, DiagnosticLoggingClient& diagnosticLoggingClient, unsigned indentLevel)
 {
     PCLOG("+---");
-    if (!frame->loader().documentLoader()) {
+    FrameLoader& frameLoader = frame.loader();
+
+    // Prevent page caching if a subframe is still in provisional load stage.
+    // We only do this check for subframes because the main frame is reused when navigating to a new page.
+    if (!frame.isMainFrame() && frameLoader.state() == FrameStateProvisional) {
+        PCLOG("   -Frame is in provisional load stage");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::provisionalLoadKey());
+        return false;
+    }
+
+    DocumentLoader* documentLoader = frameLoader.documentLoader();
+    if (!documentLoader) {
         PCLOG("   -There is no DocumentLoader object");
-        return 1 << NoDocumentLoader;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::noDocumentLoaderKey());
+        return false;
     }
 
-    URL currentURL = frame->loader().documentLoader()->url();
-    URL newURL = frame->loader().provisionalDocumentLoader() ? frame->loader().provisionalDocumentLoader()->url() : URL();
+    URL currentURL = documentLoader->url();
+    URL newURL = frameLoader.provisionalDocumentLoader() ? frameLoader.provisionalDocumentLoader()->url() : URL();
     if (!newURL.isEmpty())
         PCLOG(" Determining if frame can be cached navigating from (", currentURL.string(), ") to (", newURL.string(), "):");
     else
         PCLOG(" Determining if subframe with URL (", currentURL.string(), ") can be cached:");
      
-    unsigned rejectReasons = 0;
-    if (!frame->loader().documentLoader()->mainDocumentError().isNull()) {
+    bool isCacheable = true;
+    if (!documentLoader->mainDocumentError().isNull()) {
         PCLOG("   -Main document has an error");
-#if !PLATFORM(IOS)
-        rejectReasons |= 1 << MainDocumentError;
-#else
-        if (frame->loader().documentLoader()->mainDocumentError().isCancellation() && frame->loader().documentLoader()->subresourceLoadersArePageCacheAcceptable())
-            PCLOG("    -But, it was a cancellation and all loaders during the cancel were loading images.");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::mainDocumentErrorKey());
+
+        if (documentLoader->mainDocumentError().isCancellation() && documentLoader->subresourceLoadersArePageCacheAcceptable())
+            PCLOG("    -But, it was a cancellation and all loaders during the cancelation were loading images or XHR.");
         else
-            rejectReasons |= 1 << MainDocumentError;
-#endif
+            isCacheable = false;
     }
-    if (frame->loader().documentLoader()->substituteData().isValid() && frame->loader().documentLoader()->substituteData().failingURL().isEmpty()) {
+    // Do not cache error pages (these can be recognized as pages with substitute data or unreachable URLs).
+    if (documentLoader->substituteData().isValid() && !documentLoader->substituteData().failingURL().isEmpty()) {
         PCLOG("   -Frame is an error page");
-        rejectReasons |= 1 << IsErrorPage;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::isErrorPageKey());
+        isCacheable = false;
     }
-    if (frame->loader().subframeLoader().containsPlugins() && !frame->page()->settings().pageCacheSupportsPlugins()) {
+    if (frameLoader.subframeLoader().containsPlugins() && !frame.page()->settings().pageCacheSupportsPlugins()) {
         PCLOG("   -Frame contains plugins");
-        rejectReasons |= 1 << HasPlugins;
-    }
-    if (frame->document()->url().protocolIs("https")
-        && (frame->loader().documentLoader()->response().cacheControlContainsNoCache()
-            || frame->loader().documentLoader()->response().cacheControlContainsNoStore())) {
-        PCLOG("   -Frame is HTTPS, and cache control prohibits caching or storing");
-        rejectReasons |= 1 << IsHttpsAndCacheControlled;
-    }
-    if (frame->document()->domWindow() && frame->document()->domWindow()->hasEventListeners(eventNames().unloadEvent)) {
-        PCLOG("   -Frame has an unload event listener");
-#if !PLATFORM(IOS)
-        rejectReasons |= 1 << HasUnloadListener;
-#else
-        // iOS allows pages with unload event listeners to enter the page cache.
-        PCLOG("    -BUT iOS allows these pages to be cached.");
-#endif
-    }
-#if ENABLE(SQL_DATABASE)
-    if (DatabaseManager::manager().hasOpenDatabases(frame->document())) {
-        PCLOG("   -Frame has open database handles");
-        rejectReasons |= 1 << HasDatabaseHandles;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::hasPluginsKey());
+        isCacheable = false;
     }
-#endif
-#if ENABLE(SHARED_WORKERS)
-    if (SharedWorkerRepository::hasSharedWorkers(frame->document())) {
-        PCLOG("   -Frame has associated SharedWorkers");
-        rejectReasons |= 1 << HasSharedWorkers;
+    if (frame.isMainFrame() && frame.document() && frame.document()->url().protocolIs("https") && documentLoader->response().cacheControlContainsNoStore()) {
+        PCLOG("   -Frame is HTTPS, and cache control prohibits storing");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::httpsNoStoreKey());
+        isCacheable = false;
     }
-#endif
-    if (!frame->loader().history().currentItem()) {
-        PCLOG("   -No current history item");
-        rejectReasons |= 1 << NoHistoryItem;
+    if (frame.isMainFrame() && !frameLoader.history().currentItem()) {
+        PCLOG("   -Main frame has no current history item");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::noCurrentHistoryItemKey());
+        isCacheable = false;
     }
-    if (frame->loader().quickRedirectComing()) {
+    if (frameLoader.quickRedirectComing()) {
         PCLOG("   -Quick redirect is coming");
-        rejectReasons |= 1 << QuickRedirectComing;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::quirkRedirectComingKey());
+        isCacheable = false;
     }
-    if (frame->loader().documentLoader()->isLoadingInAPISense()) {
-        PCLOG("   -DocumentLoader is still loading in API sense");
-        rejectReasons |= 1 << IsLoadingInAPISense;
+    if (documentLoader->isLoading()) {
+        PCLOG("   -DocumentLoader is still loading");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::isLoadingKey());
+        isCacheable = false;
     }
-    if (frame->loader().documentLoader()->isStopping()) {
+    if (documentLoader->isStopping()) {
         PCLOG("   -DocumentLoader is in the middle of stopping");
-        rejectReasons |= 1 << IsStopping;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::documentLoaderStoppingKey());
+        isCacheable = false;
     }
-    if (!frame->document()->canSuspendActiveDOMObjects()) {
-        PCLOG("   -The document cannot suspect its active DOM Objects");
-        rejectReasons |= 1 << CannotSuspendActiveDOMObjects;
+
+    Vector<ActiveDOMObject*> unsuspendableObjects;
+    if (frame.document() && !frame.document()->canSuspendActiveDOMObjectsForDocumentSuspension(&unsuspendableObjects)) {
+        PCLOG("   -The document cannot suspend its active DOM Objects");
+        for (auto* activeDOMObject : unsuspendableObjects) {
+            PCLOG("    - Unsuspendable: ", activeDOMObject->activeDOMObjectName());
+            diagnosticLoggingClient.logDiagnosticMessage(DiagnosticLoggingKeys::unsuspendableDOMObjectKey(), activeDOMObject->activeDOMObjectName(), ShouldSample::Yes);
+            UNUSED_PARAM(activeDOMObject);
+        }
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::cannotSuspendActiveDOMObjectsKey());
+        isCacheable = false;
     }
-    if (!frame->loader().documentLoader()->applicationCacheHost()->canCacheInPageCache()) {
+    // FIXME: We should investigating caching frames that have an associated
+    // application cache. <rdar://problem/5917899> tracks that work.
+    if (!documentLoader->applicationCacheHost().canCacheInPageCache()) {
         PCLOG("   -The DocumentLoader uses an application cache");
-        rejectReasons |= 1 << DocumentLoaderUsesApplicationCache;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::applicationCacheKey());
+        isCacheable = false;
     }
-    if (!frame->loader().client().canCachePage()) {
+    if (!frameLoader.client().canCachePage()) {
         PCLOG("   -The client says this frame cannot be cached");
-        rejectReasons |= 1 << ClientDeniesCaching;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::deniedByClientKey());
+        isCacheable = false;
     }
 
-    HistogramSupport::histogramEnumeration("PageCache.FrameCacheable", !rejectReasons, 2);
-    int reasonCount = 0;
-    for (int i = 0; i < NumberOfReasonsFramesCannotBeInPageCache; ++i) {
-        if (rejectReasons & (1 << i)) {
-            ++reasonCount;
-            HistogramSupport::histogramEnumeration("PageCache.FrameRejectReason", i, NumberOfReasonsFramesCannotBeInPageCache);
-        }
+    for (Frame* child = frame.tree().firstChild(); child; child = child->tree().nextSibling()) {
+        if (!canCacheFrame(*child, diagnosticLoggingClient, indentLevel + 1))
+            isCacheable = false;
     }
-    HistogramSupport::histogramEnumeration("PageCache.FrameRejectReasonCount", reasonCount, 1 + NumberOfReasonsFramesCannotBeInPageCache);
-
-    for (Frame* child = frame->tree().firstChild(); child; child = child->tree().nextSibling())
-        rejectReasons |= logCanCacheFrameDecision(child, indentLevel + 1);
     
-    PCLOG(rejectReasons ? " Frame CANNOT be cached" : " Frame CAN be cached");
+    PCLOG(isCacheable ? " Frame CAN be cached" : " Frame CANNOT be cached");
     PCLOG("+---");
     
-    return rejectReasons;
+    return isCacheable;
 }
 
-// Used in histograms, please only add at the end, and do not remove elements (renaming e.g. to "FooEnumUnused1" is fine).
-// This is because statistics may be gathered from histograms between versions over time, and re-using values causes collisions.
-enum ReasonPageCannotBeInPageCache {
-    FrameCannotBeInPageCache = 0,
-    DisabledBackForwardList,
-    DisabledPageCache,
-    UsesDeviceMotion,
-    UsesDeviceOrientation,
-    IsReload,
-    IsReloadFromOrigin,
-    IsSameLoad,
-    NumberOfReasonsPagesCannotBeInPageCache,
-};
-COMPILE_ASSERT(NumberOfReasonsPagesCannotBeInPageCache <= sizeof(unsigned)*8, ReasonPageCannotBeInPageCacheDoesNotFitInBitmap);
-
-static void logCanCachePageDecision(Page* page)
+static bool canCachePage(Page& page)
 {
-    // Only bother logging for main frames that have actually loaded and have content.
-    if (page->mainFrame().loader().stateMachine()->creatingInitialEmptyDocument())
-        return;
-    URL currentURL = page->mainFrame().loader().documentLoader() ? page->mainFrame().loader().documentLoader()->url() : URL();
-    if (currentURL.isEmpty())
-        return;
-    
-    int indentLevel = 0;    
+    unsigned indentLevel = 0;
     PCLOG("--------\n Determining if page can be cached:");
+
+    DiagnosticLoggingClient& diagnosticLoggingClient = page.diagnosticLoggingClient();
+    bool isCacheable = canCacheFrame(page.mainFrame(), diagnosticLoggingClient, indentLevel + 1);
     
-    unsigned rejectReasons = 0;
-    unsigned frameRejectReasons = logCanCacheFrameDecision(&page->mainFrame(), indentLevel+1);
-    if (frameRejectReasons)
-        rejectReasons |= 1 << FrameCannotBeInPageCache;
-    
-    if (!page->settings().usesPageCache()) {
+    if (!page.settings().usesPageCache() || page.isResourceCachingDisabled()) {
         PCLOG("   -Page settings says b/f cache disabled");
-        rejectReasons |= 1 << DisabledPageCache;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::isDisabledKey());
+        isCacheable = false;
     }
 #if ENABLE(DEVICE_ORIENTATION) && !PLATFORM(IOS)
-    if (DeviceMotionController::isActiveAt(page)) {
+    if (DeviceMotionController::isActiveAt(&page)) {
         PCLOG("   -Page is using DeviceMotion");
-        rejectReasons |= 1 << UsesDeviceMotion;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::deviceMotionKey());
+        isCacheable = false;
     }
-    if (DeviceOrientationController::isActiveAt(page)) {
+    if (DeviceOrientationController::isActiveAt(&page)) {
         PCLOG("   -Page is using DeviceOrientation");
-        rejectReasons |= 1 << UsesDeviceOrientation;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::deviceOrientationKey());
+        isCacheable = false;
     }
 #endif
 #if ENABLE(PROXIMITY_EVENTS)
     if (DeviceProximityController::isActiveAt(page)) {
         PCLOG("   -Page is using DeviceProximity");
-        rejectReasons |= 1 << UsesDeviceMotion;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, deviceProximityKey);
+        isCacheable = false;
     }
 #endif
-    FrameLoadType loadType = page->mainFrame().loader().loadType();
-    if (loadType == FrameLoadTypeReload) {
+    FrameLoadType loadType = page.mainFrame().loader().loadType();
+    switch (loadType) {
+    case FrameLoadType::Reload:
+        // No point writing to the cache on a reload, since we will just write over it again when we leave that page.
         PCLOG("   -Load type is: Reload");
-        rejectReasons |= 1 << IsReload;
-    }
-    if (loadType == FrameLoadTypeReloadFromOrigin) {
-        PCLOG("   -Load type is: Reload from origin");
-        rejectReasons |= 1 << IsReloadFromOrigin;
-    }
-    if (loadType == FrameLoadTypeSame) {
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::reloadKey());
+        isCacheable = false;
+        break;
+    case FrameLoadType::Same: // user loads same URL again (but not reload button)
+        // No point writing to the cache on a same load, since we will just write over it again when we leave that page.
         PCLOG("   -Load type is: Same");
-        rejectReasons |= 1 << IsSameLoad;
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::sameLoadKey());
+        isCacheable = false;
+        break;
+    case FrameLoadType::RedirectWithLockedBackForwardList:
+        // Don't write to the cache if in the middle of a redirect, since we will want to store the final page we end up on.
+        PCLOG("   -Load type is: RedirectWithLockedBackForwardList");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::redirectKey());
+        isCacheable = false;
+        break;
+    case FrameLoadType::Replace:
+        // No point writing to the cache on a replace, since we will just write over it again when we leave that page.
+        PCLOG("   -Load type is: Replace");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::replaceKey());
+        isCacheable = false;
+        break;
+    case FrameLoadType::ReloadFromOrigin: {
+        // No point writing to the cache on a reload, since we will just write over it again when we leave that page.
+        PCLOG("   -Load type is: ReloadFromOrigin");
+        logPageCacheFailureDiagnosticMessage(diagnosticLoggingClient, DiagnosticLoggingKeys::reloadFromOriginKey());
+        isCacheable = false;
+        break;
+    }
+    case FrameLoadType::Standard:
+    case FrameLoadType::Back:
+    case FrameLoadType::Forward:
+    case FrameLoadType::IndexedBackForward: // a multi-item hop in the backforward list
+        // Cacheable.
+        break;
     }
     
-    PCLOG(rejectReasons ? " Page CANNOT be cached\n--------" : " Page CAN be cached\n--------");
-
-    HistogramSupport::histogramEnumeration("PageCache.PageCacheable", !rejectReasons, 2);
-    int reasonCount = 0;
-    for (int i = 0; i < NumberOfReasonsPagesCannotBeInPageCache; ++i) {
-        if (rejectReasons & (1 << i)) {
-            ++reasonCount;
-            HistogramSupport::histogramEnumeration("PageCache.PageRejectReason", i, NumberOfReasonsPagesCannotBeInPageCache);
-        }
-    }
-    HistogramSupport::histogramEnumeration("PageCache.PageRejectReasonCount", reasonCount, 1 + NumberOfReasonsPagesCannotBeInPageCache);
-    const bool settingsDisabledPageCache = rejectReasons & (1 << DisabledPageCache);
-    HistogramSupport::histogramEnumeration("PageCache.PageRejectReasonCountExcludingSettings", reasonCount - settingsDisabledPageCache, NumberOfReasonsPagesCannotBeInPageCache);
-
-    // Report also on the frame reasons by page; this is distinct from the per frame statistics since it coalesces the
-    // causes from all subframes together.
-    HistogramSupport::histogramEnumeration("PageCache.FrameCacheableByPage", !frameRejectReasons, 2);
-    int frameReasonCount = 0;
-    for (int i = 0; i <= NumberOfReasonsFramesCannotBeInPageCache; ++i) {
-        if (frameRejectReasons & (1 << i)) {
-            ++frameReasonCount;
-            HistogramSupport::histogramEnumeration("PageCache.FrameRejectReasonByPage", i, NumberOfReasonsFramesCannotBeInPageCache);
-        }
-    }
-
-    HistogramSupport::histogramEnumeration("PageCache.FrameRejectReasonCountByPage", frameReasonCount, 1 + NumberOfReasonsFramesCannotBeInPageCache);
-}
-
-#endif // !defined(NDEBUG)
+    if (isCacheable)
+        PCLOG(" Page CAN be cached\n--------");
+    else
+        PCLOG(" Page CANNOT be cached\n--------");
 
-PageCache* pageCache()
-{
-    static PageCache* staticPageCache = new PageCache;
-    return staticPageCache;
+    diagnosticLoggingClient.logDiagnosticMessageWithResult(DiagnosticLoggingKeys::pageCacheKey(), DiagnosticLoggingKeys::canCacheKey(), isCacheable ? DiagnosticLoggingResultPass : DiagnosticLoggingResultFail, ShouldSample::Yes);
+    return isCacheable;
 }
 
-PageCache::PageCache()
-    : m_capacity(0)
-    , m_size(0)
-    , m_head(0)
-    , m_tail(0)
-#if USE(ACCELERATED_COMPOSITING)
-    , m_shouldClearBackingStores(false)
-#endif
+PageCache& PageCache::singleton()
 {
+    static NeverDestroyed<PageCache> globalPageCache;
+    return globalPageCache;
 }
     
-bool PageCache::canCachePageContainingThisFrame(Frame* frame)
+bool PageCache::canCache(Page& page) const
 {
-    for (Frame* child = frame->tree().firstChild(); child; child = child->tree().nextSibling()) {
-        if (!canCachePageContainingThisFrame(child))
-            return false;
-    }
-    
-    FrameLoader& frameLoader = frame->loader();
-    DocumentLoader* documentLoader = frameLoader.documentLoader();
-    Document* document = frame->document();
-    
-    return documentLoader
-#if !PLATFORM(IOS)
-        && documentLoader->mainDocumentError().isNull()
-#else
-        && (documentLoader->mainDocumentError().isNull() || (documentLoader->mainDocumentError().isCancellation() && documentLoader->subresourceLoadersArePageCacheAcceptable()))
-#endif
-        // Do not cache error pages (these can be recognized as pages with substitute data or unreachable URLs).
-        && !(documentLoader->substituteData().isValid() && !documentLoader->substituteData().failingURL().isEmpty())
-        && (!frameLoader.subframeLoader().containsPlugins() || frame->page()->settings().pageCacheSupportsPlugins())
-        && (!document->url().protocolIs("https") || (!documentLoader->response().cacheControlContainsNoCache() && !documentLoader->response().cacheControlContainsNoStore()))
-#if !PLATFORM(IOS)
-        && (!document->domWindow() || !document->domWindow()->hasEventListeners(eventNames().unloadEvent))
-#endif
-#if ENABLE(SQL_DATABASE)
-        && !DatabaseManager::manager().hasOpenDatabases(document)
-#endif
-#if ENABLE(SHARED_WORKERS)
-        && !SharedWorkerRepository::hasSharedWorkers(document)
-#endif
-        && frameLoader.history().currentItem()
-        && !frameLoader.quickRedirectComing()
-        && !documentLoader->isLoadingInAPISense()
-        && !documentLoader->isStopping()
-        && document->canSuspendActiveDOMObjects()
-        // FIXME: We should investigating caching frames that have an associated
-        // application cache. <rdar://problem/5917899> tracks that work.
-        && documentLoader->applicationCacheHost()->canCacheInPageCache()
-        && frameLoader.client().canCachePage();
-}
-    
-bool PageCache::canCache(Page* page) const
-{
-    if (!page)
+    if (!m_maxSize) {
+        logPageCacheFailureDiagnosticMessage(&page, DiagnosticLoggingKeys::isDisabledKey());
         return false;
-    
-#if !defined(NDEBUG)
-    logCanCachePageDecision(page);
-#endif
+    }
 
-#if PLATFORM(IOS)
-    if (memoryPressureHandler().hasReceivedMemoryPressure())
+    if (MemoryPressureHandler::singleton().isUnderMemoryPressure()) {
+        logPageCacheFailureDiagnosticMessage(&page, DiagnosticLoggingKeys::underMemoryPressureKey());
         return false;
-#endif
-
-    // Cache the page, if possible.
-    // Don't write to the cache if in the middle of a redirect, since we will want to
-    // store the final page we end up on.
-    // No point writing to the cache on a reload or loadSame, since we will just write
-    // over it again when we leave that page.
-    FrameLoadType loadType = page->mainFrame().loader().loadType();
+    }
     
-    return m_capacity > 0
-        && canCachePageContainingThisFrame(&page->mainFrame())
-        && page->settings().usesPageCache()
-#if ENABLE(DEVICE_ORIENTATION) && !PLATFORM(IOS)
-        && !DeviceMotionController::isActiveAt(page)
-        && !DeviceOrientationController::isActiveAt(page)
-#endif
-#if ENABLE(PROXIMITY_EVENTS)
-        && !DeviceProximityController::isActiveAt(page)
-#endif
-        && (loadType == FrameLoadTypeStandard
-            || loadType == FrameLoadTypeBack
-            || loadType == FrameLoadTypeForward
-            || loadType == FrameLoadTypeIndexedBackForward);
+    return canCachePage(page);
 }
 
-void PageCache::pruneToCapacityNow(int capacity)
+void PageCache::pruneToSizeNow(unsigned size, PruningReason pruningReason)
 {
-    int savedCapacity = m_capacity;
-    setCapacity(capacity);
-    setCapacity(savedCapacity);
+    SetForScope<unsigned> change(m_maxSize, size);
+    prune(pruningReason);
 }
 
-void PageCache::setCapacity(int capacity)
+void PageCache::setMaxSize(unsigned maxSize)
 {
-    ASSERT(capacity >= 0);
-    m_capacity = std::max(capacity, 0);
-
-    prune();
+    m_maxSize = maxSize;
+    prune(PruningReason::None);
 }
 
-int PageCache::frameCount() const
+unsigned PageCache::frameCount() const
 {
-    int frameCount = 0;
-    for (HistoryItem* current = m_head; current; current = current->m_next) {
-        ++frameCount;
-        ASSERT(current->m_cachedPage);
-        frameCount += current->m_cachedPage ? current->m_cachedPage->cachedMainFrame()->descendantFrameCount() : 0;
+    unsigned frameCount = m_items.size();
+    for (auto& item : m_items) {
+        ASSERT(item->m_cachedPage);
+        frameCount += item->m_cachedPage->cachedMainFrame()->descendantFrameCount();
     }
     
     return frameCount;
 }
 
-void PageCache::markPagesForVistedLinkStyleRecalc()
+void PageCache::markPagesForDeviceOrPageScaleChanged(Page& page)
 {
-    for (HistoryItem* current = m_head; current; current = current->m_next) {
-        if (current->m_cachedPage)
-            current->m_cachedPage->markForVistedLinkStyleRecalc();
+    for (auto& item : m_items) {
+        CachedPage& cachedPage = *item->m_cachedPage;
+        if (&page.mainFrame() == &cachedPage.cachedMainFrame()->view()->frame())
+            cachedPage.markForDeviceOrPageScaleChanged();
     }
 }
 
-void PageCache::markPagesForFullStyleRecalc(Page* page)
+void PageCache::markPagesForContentsSizeChanged(Page& page)
 {
-    for (HistoryItem* current = m_head; current; current = current->m_next) {
-        CachedPage* cachedPage = current->m_cachedPage.get();
-        if (cachedPage && &page->mainFrame() == &cachedPage->cachedMainFrame()->view()->frame())
-            cachedPage->markForFullStyleRecalc();
+    for (auto& item : m_items) {
+        CachedPage& cachedPage = *item->m_cachedPage;
+        if (&page.mainFrame() == &cachedPage.cachedMainFrame()->view()->frame())
+            cachedPage.markForContentsSizeChanged();
     }
 }
 
-
-#if USE(ACCELERATED_COMPOSITING)
-void PageCache::markPagesForDeviceScaleChanged(Page* page)
+#if ENABLE(VIDEO_TRACK)
+void PageCache::markPagesForCaptionPreferencesChanged()
 {
-    for (HistoryItem* current = m_head; current; current = current->m_next) {
-        CachedPage* cachedPage = current->m_cachedPage.get();
-        if (cachedPage && &page->mainFrame() == &cachedPage->cachedMainFrame()->view()->frame())
-            cachedPage->markForDeviceScaleChanged();
+    for (auto& item : m_items) {
+        ASSERT(item->m_cachedPage);
+        item->m_cachedPage->markForCaptionPreferencesChanged();
     }
 }
 #endif
 
-#if ENABLE(VIDEO_TRACK)
-void PageCache::markPagesForCaptionPreferencesChanged()
+static String pruningReasonToDiagnosticLoggingKey(PruningReason pruningReason)
+{
+    switch (pruningReason) {
+    case PruningReason::MemoryPressure:
+        return DiagnosticLoggingKeys::prunedDueToMemoryPressureKey();
+    case PruningReason::ProcessSuspended:
+        return DiagnosticLoggingKeys::prunedDueToProcessSuspended();
+    case PruningReason::ReachedMaxSize:
+        return DiagnosticLoggingKeys::prunedDueToMaxSizeReached();
+    case PruningReason::None:
+        break;
+    }
+    ASSERT_NOT_REACHED();
+    return emptyString();
+}
+
+static void setPageCacheState(Page& page, Document::PageCacheState pageCacheState)
 {
-    for (HistoryItem* current = m_head; current; current = current->m_next) {
-        if (current->m_cachedPage)
-            current->m_cachedPage->markForCaptionPreferencesChanged();
+    for (Frame* frame = &page.mainFrame(); frame; frame = frame->tree().traverseNext()) {
+        if (auto* document = frame->document())
+            document->setPageCacheState(pageCacheState);
     }
 }
-#endif
 
-void PageCache::add(PassRefPtr<HistoryItem> prpItem, Page& page)
+// When entering page cache, tear down the render tree before setting the in-cache flag.
+// This maintains the invariant that render trees are never present in the page cache.
+// Note that destruction happens bottom-up so that the main frame's tree dies last.
+static void destroyRenderTree(MainFrame& mainFrame)
 {
-    ASSERT(prpItem);
-    ASSERT(canCache(&page));
-    
-    HistoryItem* item = prpItem.leakRef(); // Balanced in remove().
+    for (Frame* frame = mainFrame.tree().traversePreviousWithWrap(true); frame; frame = frame->tree().traversePreviousWithWrap(false)) {
+        if (!frame->document())
+            continue;
+        auto& document = *frame->document();
+        if (document.hasLivingRenderTree())
+            document.destroyRenderTree();
+    }
+}
 
-    // Remove stale cache entry if necessary.
-    if (item->m_cachedPage)
-        remove(item);
+static void firePageHideEventRecursively(Frame& frame)
+{
+    auto* document = frame.document();
+    if (!document)
+        return;
 
-    item->m_cachedPage = std::make_unique<CachedPage>(page);
-    addToLRUList(item);
-    ++m_size;
-    
-    prune();
+    // stopLoading() will fire the pagehide event in each subframe and the HTML specification states
+    // that the parent document's ignore-opens-during-unload counter should be incremented while the
+    // pagehide event is being fired in its subframes:
+    // https://html.spec.whatwg.org/multipage/browsers.html#unload-a-document
+    IgnoreOpensDuringUnloadCountIncrementer ignoreOpensDuringUnloadCountIncrementer(document);
+
+    frame.loader().stopLoading(UnloadEventPolicyUnloadAndPageHide);
+
+    for (RefPtr<Frame> child = frame.tree().firstChild(); child; child = child->tree().nextSibling())
+        firePageHideEventRecursively(*child);
 }
 
-std::unique_ptr<CachedPage> PageCache::take(HistoryItem* item)
+void PageCache::addIfCacheable(HistoryItem& item, Page* page)
 {
-    if (!item)
-        return nullptr;
+    if (item.isInPageCache())
+        return;
 
-    std::unique_ptr<CachedPage> cachedPage = std::move(item->m_cachedPage);
+    if (!page || !canCache(*page))
+        return;
 
-    removeFromLRUList(item);
-    --m_size;
+    setPageCacheState(*page, Document::AboutToEnterPageCache);
 
-    item->deref(); // Balanced in add().
+    // Focus the main frame, defocusing a focused subframe (if we have one). We do this here,
+    // before the page enters the page cache, while we still can dispatch DOM blur/focus events.
+    if (page->focusController().focusedFrame())
+        page->focusController().setFocusedFrame(&page->mainFrame());
 
-    if (!cachedPage)
-        return nullptr;
+    // Fire the pagehide event in all frames.
+    firePageHideEventRecursively(page->mainFrame());
 
-    if (cachedPage->hasExpired()) {
-        LOG(PageCache, "Not restoring page for %s from back/forward cache because cache entry has expired", item->url().string().ascii().data());
-        return nullptr;
+    // Check that the page is still page-cacheable after firing the pagehide event. The JS event handlers
+    // could have altered the page in a way that could prevent caching.
+    if (!canCache(*page)) {
+        setPageCacheState(*page, Document::NotInPageCache);
+        return;
     }
 
-    return cachedPage;
-}
+    destroyRenderTree(page->mainFrame());
 
-CachedPage* PageCache::get(HistoryItem* item)
-{
-    if (!item)
-        return 0;
+    setPageCacheState(*page, Document::InPageCache);
 
-    if (CachedPage* cachedPage = item->m_cachedPage.get()) {
-        if (!cachedPage->hasExpired())
-            return cachedPage;
-        
-        LOG(PageCache, "Not restoring page for %s from back/forward cache because cache entry has expired", item->url().string().ascii().data());
-        pageCache()->remove(item);
-    }
-    return 0;
+    // Make sure we no longer fire any JS events past this point.
+    NoEventDispatchAssertion assertNoEventDispatch;
+
+    item.m_cachedPage = std::make_unique<CachedPage>(*page);
+    item.m_pruningReason = PruningReason::None;
+    m_items.add(&item);
+    
+    prune(PruningReason::ReachedMaxSize);
 }
 
-void PageCache::remove(HistoryItem* item)
+std::unique_ptr<CachedPage> PageCache::take(HistoryItem& item, Page* page)
 {
-    // Safely ignore attempts to remove items not in the cache.
-    if (!item || !item->m_cachedPage)
-        return;
+    if (!item.m_cachedPage) {
+        if (item.m_pruningReason != PruningReason::None)
+            logPageCacheFailureDiagnosticMessage(page, pruningReasonToDiagnosticLoggingKey(item.m_pruningReason));
+        return nullptr;
+    }
 
-    item->m_cachedPage = nullptr;
-    removeFromLRUList(item);
-    --m_size;
+    m_items.remove(&item);
+    std::unique_ptr<CachedPage> cachedPage = WTFMove(item.m_cachedPage);
 
-    item->deref(); // Balanced in add().
+    if (cachedPage->hasExpired() || (page && page->isResourceCachingDisabled())) {
+        LOG(PageCache, "Not restoring page for %s from back/forward cache because cache entry has expired", item.url().string().ascii().data());
+        logPageCacheFailureDiagnosticMessage(page, DiagnosticLoggingKeys::expiredKey());
+        return nullptr;
+    }
+
+    return cachedPage;
 }
 
-void PageCache::prune()
+void PageCache::removeAllItemsForPage(Page& page)
 {
-    while (m_size > m_capacity) {
-        ASSERT(m_tail && m_tail->m_cachedPage);
-        remove(m_tail);
+    for (auto it = m_items.begin(); it != m_items.end();) {
+        // Increment iterator first so it stays valid after the removal.
+        auto current = it;
+        ++it;
+        if (&(*current)->m_cachedPage->page() == &page) {
+            (*current)->m_cachedPage = nullptr;
+            m_items.remove(current);
+        }
     }
 }
 
-void PageCache::addToLRUList(HistoryItem* item)
+CachedPage* PageCache::get(HistoryItem& item, Page* page)
 {
-    item->m_next = m_head;
-    item->m_prev = 0;
+    CachedPage* cachedPage = item.m_cachedPage.get();
+    if (!cachedPage) {
+        if (item.m_pruningReason != PruningReason::None)
+            logPageCacheFailureDiagnosticMessage(page, pruningReasonToDiagnosticLoggingKey(item.m_pruningReason));
+        return nullptr;
+    }
 
-    if (m_head) {
-        ASSERT(m_tail);
-        m_head->m_prev = item;
-    } else {
-        ASSERT(!m_tail);
-        m_tail = item;
+    if (cachedPage->hasExpired() || (page && page->isResourceCachingDisabled())) {
+        LOG(PageCache, "Not restoring page for %s from back/forward cache because cache entry has expired", item.url().string().ascii().data());
+        logPageCacheFailureDiagnosticMessage(page, DiagnosticLoggingKeys::expiredKey());
+        remove(item);
+        return nullptr;
     }
+    return cachedPage;
+}
+
+void PageCache::remove(HistoryItem& item)
+{
+    // Safely ignore attempts to remove items not in the cache.
+    if (!item.m_cachedPage)
+        return;
 
-    m_head = item;
+    m_items.remove(&item);
+    item.m_cachedPage = nullptr;
 }
 
-void PageCache::removeFromLRUList(HistoryItem* item)
+void PageCache::prune(PruningReason pruningReason)
 {
-    if (!item->m_next) {
-        ASSERT(item == m_tail);
-        m_tail = item->m_prev;
-    } else {
-        ASSERT(item != m_tail);
-        item->m_next->m_prev = item->m_prev;
-    }
-
-    if (!item->m_prev) {
-        ASSERT(item == m_head);
-        m_head = item->m_next;
-    } else {
-        ASSERT(item != m_head);
-        item->m_prev->m_next = item->m_next;
+    while (pageCount() > maxSize()) {
+        auto oldestItem = m_items.takeFirst();
+        oldestItem->m_cachedPage = nullptr;
+        oldestItem->m_pruningReason = pruningReason;
     }
 }
 
diff --git a/Source/WebCore/history/PageCache.h b/Source/WebCore/history/PageCache.h
index ebab10c1e..edda9e755 100644
--- a/Source/WebCore/history/PageCache.h
+++ b/Source/WebCore/history/PageCache.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 Apple Inc.  All rights reserved.
+ * Copyright (C) 2007, 2015 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -23,83 +23,63 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
-#ifndef PageCache_h
-#define PageCache_h
+#pragma once
 
+#include "HistoryItem.h"
 #include "Timer.h"
 #include <wtf/Forward.h>
-#include <wtf/HashSet.h>
+#include <wtf/ListHashSet.h>
 #include <wtf/Noncopyable.h>
 
 namespace WebCore {
 
-    class CachedPage;
-    class Frame;
-    class HistoryItem;
-    class Page;
-    
-    class PageCache {
-        WTF_MAKE_NONCOPYABLE(PageCache); WTF_MAKE_FAST_ALLOCATED;
-    public:
-        friend PageCache* pageCache();
-        
-        bool canCache(Page*) const;
-
-        void setCapacity(int); // number of pages to cache
-        int capacity() { return m_capacity; }
-        
-        void add(PassRefPtr<HistoryItem>, Page&); // Prunes if capacity() is exceeded.
-        void remove(HistoryItem*);
-        CachedPage* get(HistoryItem* item);
-        std::unique_ptr<CachedPage> take(HistoryItem*);
-
-        int pageCount() const { return m_size; }
-        int frameCount() const;
-
-        void markPagesForVistedLinkStyleRecalc();
-
-        // Will mark all cached pages associated with the given page as needing style recalc.
-        void markPagesForFullStyleRecalc(Page*);
-
-        // Used when memory is low to prune some cached pages.
-        void pruneToCapacityNow(int capacity);
+class CachedPage;
+class Frame;
+class Page;
 
-#if ENABLE(VIDEO_TRACK)
-        void markPagesForCaptionPreferencesChanged();
-#endif
+enum class PruningReason { None, ProcessSuspended, MemoryPressure, ReachedMaxSize };
 
-#if USE(ACCELERATED_COMPOSITING)
-        bool shouldClearBackingStores() const { return m_shouldClearBackingStores; }
-        void setShouldClearBackingStores(bool flag) { m_shouldClearBackingStores = flag; }
-        void markPagesForDeviceScaleChanged(Page*);
-#endif
+class PageCache {
+    WTF_MAKE_NONCOPYABLE(PageCache); WTF_MAKE_FAST_ALLOCATED;
+public:
+    // Function to obtain the global page cache.
+    WEBCORE_EXPORT static PageCache& singleton();
+
+    bool canCache(Page&) const;
 
-    private:
-        PageCache(); // Use pageCache() instead.
-        ~PageCache(); // Not implemented to make sure nobody accidentally calls delete -- WebCore does not delete singletons.
-        
-        static bool canCachePageContainingThisFrame(Frame*);
+    // Used when memory is low to prune some cached pages.
+    WEBCORE_EXPORT void pruneToSizeNow(unsigned maxSize, PruningReason);
+    WEBCORE_EXPORT void setMaxSize(unsigned); // number of pages to cache.
+    unsigned maxSize() const { return m_maxSize; }
 
-        void addToLRUList(HistoryItem*); // Adds to the head of the list.
-        void removeFromLRUList(HistoryItem*);
+    void addIfCacheable(HistoryItem&, Page*); // Prunes if maxSize() is exceeded.
+    WEBCORE_EXPORT void remove(HistoryItem&);
+    CachedPage* get(HistoryItem&, Page*);
+    std::unique_ptr<CachedPage> take(HistoryItem&, Page*);
 
-        void prune();
+    void removeAllItemsForPage(Page&);
 
-        int m_capacity;
-        int m_size;
+    unsigned pageCount() const { return m_items.size(); }
+    WEBCORE_EXPORT unsigned frameCount() const;
 
-        // LRU List
-        HistoryItem* m_head;
-        HistoryItem* m_tail;
-        
-#if USE(ACCELERATED_COMPOSITING)
-        bool m_shouldClearBackingStores;
+    void markPagesForDeviceOrPageScaleChanged(Page&);
+    void markPagesForContentsSizeChanged(Page&);
+#if ENABLE(VIDEO_TRACK)
+    void markPagesForCaptionPreferencesChanged();
 #endif
-     };
 
-    // Function to obtain the global page cache.
-    PageCache* pageCache();
+private:
+    PageCache() = default; // Use singleton() instead.
+    ~PageCache() = delete; // Make sure nobody accidentally calls delete -- WebCore does not delete singletons.
 
-} // namespace WebCore
+    static bool canCachePageContainingThisFrame(Frame&);
+
+    void prune(PruningReason);
 
-#endif // PageCache_h
+    ListHashSet<RefPtr<HistoryItem>> m_items;
+    unsigned m_maxSize {0};
+
+    friend class WTF::NeverDestroyed<PageCache>;
+};
+
+} // namespace WebCore