1 files changed, 36 insertions, 24 deletions

diff --git a/Source/WebCore/dom/ActiveDOMObject.h b/Source/WebCore/dom/ActiveDOMObject.h
index 5a1f3d121..c47b1f45a 100644
--- a/Source/WebCore/dom/ActiveDOMObject.h
+++ b/Source/WebCore/dom/ActiveDOMObject.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
@@ -24,8 +24,7 @@
  *
  */
 
-#ifndef ActiveDOMObject_h
-#define ActiveDOMObject_h
+#pragma once
 
 #include "ContextDestructionObserver.h"
 #include <wtf/Assertions.h>
@@ -35,40 +34,46 @@ namespace WebCore {
 
 class ActiveDOMObject : public ContextDestructionObserver {
 public:
-    explicit ActiveDOMObject(ScriptExecutionContext*);
-
-    // suspendIfNeeded() should be called exactly once after object construction to synchronize
-    // the suspend state with that in ScriptExecutionContext.
+    // The suspendIfNeeded must be called exactly once after object construction to update
+    // the suspended state to match that of the ScriptExecutionContext.
     void suspendIfNeeded();
-#if !ASSERT_DISABLED
-    bool suspendIfNeededCalled() const { return m_suspendIfNeededCalled; }
-#endif
+    void assertSuspendIfNeededWasCalled() const;
 
     virtual bool hasPendingActivity() const;
 
-    // canSuspend() is used by the caller if there is a choice between suspending and stopping.
-    // For example, a page won't be suspended and placed in the back/forward cache if it has
-    // the objects that can not be suspended.
-    // However, 'suspend' can be called even if canSuspend() would return 'false'. That
-    // happens in step-by-step JS debugging for example - in this case it would be incorrect
-    // to stop the object. Exact semantics of suspend is up to the object then.
+    // The canSuspendForDocumentSuspension() function is used by the caller if there is a choice between suspending
+    // and stopping. For example, a page won't be suspended and placed in the back/forward
+    // cache if it contains any objects that cannot be suspended.
+
+    // However, the suspend function will sometimes be called even if canSuspendForDocumentSuspension() returns false.
+    // That happens in step-by-step JS debugging for example - in this case it would be incorrect
+    // to stop the object. Exact semantics of suspend is up to the object in cases like that.
+
     enum ReasonForSuspension {
         JavaScriptDebuggerPaused,
         WillDeferLoading,
-        DocumentWillBecomeInactive,
+        PageCache,
         PageWillBeSuspended,
-        DocumentWillBePaused
     };
-    virtual bool canSuspend() const;
+
+    virtual const char* activeDOMObjectName() const = 0;
+
+    // These three functions must not have a side effect of creating or destroying
+    // any ActiveDOMObject. That means they must not result in calls to arbitrary JavaScript.
+    virtual bool canSuspendForDocumentSuspension() const = 0; // Returning false in canSuspendForDocumentSuspension() will prevent the page from entering the PageCache.
     virtual void suspend(ReasonForSuspension);
     virtual void resume();
+
+    // This function must not have a side effect of creating an ActiveDOMObject.
+    // That means it must not result in calls to arbitrary JavaScript.
+    // It can, however, have a side effect of deleting an ActiveDOMObject.
     virtual void stop();
 
     template<class T> void setPendingActivity(T* thisObject)
     {
         ASSERT(thisObject == this);
         thisObject->ref();
-        m_pendingActivityCount++;
+        ++m_pendingActivityCount;
     }
 
     template<class T> void unsetPendingActivity(T* thisObject)
@@ -79,15 +84,22 @@ public:
     }
 
 protected:
+    explicit ActiveDOMObject(ScriptExecutionContext*);
     virtual ~ActiveDOMObject();
 
 private:
     unsigned m_pendingActivityCount;
 #if !ASSERT_DISABLED
-    bool m_suspendIfNeededCalled;
+    bool m_suspendIfNeededWasCalled;
 #endif
 };
 
-} // namespace WebCore
+#if ASSERT_DISABLED
+
+inline void ActiveDOMObject::assertSuspendIfNeededWasCalled() const
+{
+}
 
-#endif // ActiveDOMObject_h
+#endif
+
+} // namespace WebCore