1 files changed, 96 insertions, 0 deletions
diff --git a/chromium/ui/gfx/win/singleton_hwnd_hot_key_observer.cc b/chromium/ui/gfx/win/singleton_hwnd_hot_key_observer.cc
new file mode 100644
index 00000000000..2d2363477b2
--- /dev/null
+++ b/chromium/ui/gfx/win/singleton_hwnd_hot_key_observer.cc
@@ -0,0 +1,96 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/gfx/win/singleton_hwnd_hot_key_observer.h"
+
+#include "base/bind.h"
+#include "base/containers/flat_set.h"
+#include "base/memory/ptr_util.h"
+#include "base/no_destructor.h"
+#include "base/optional.h"
+#include "ui/gfx/win/singleton_hwnd.h"
+
+namespace gfx {
+
+namespace {
+
+base::flat_set<int>& GetUsedHotKeyIDs() {
+  static base::NoDestructor<base::flat_set<int>> used_hot_key_ids;
+  return *used_hot_key_ids;
+}
+
+base::Optional<int> GetAvailableHotKeyID() {
+  // Valid hot key IDs are in the range 0x0000 to 0xBFFF. See
+  // https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-registerhotkey
+  for (int i = 0x0000; i < 0xBFFF; i++) {
+    if (!GetUsedHotKeyIDs().contains(i))
+      return i;
+  }
+  return base::nullopt;
+}
+
+void SetHotKeyIDUsed(int id) {
+  DCHECK(!GetUsedHotKeyIDs().contains(id));
+  GetUsedHotKeyIDs().insert(id);
+}
+
+void SetHotKeyIDAvailable(int id) {
+  DCHECK(GetUsedHotKeyIDs().contains(id));
+  GetUsedHotKeyIDs().erase(id);
+}
+
+}  // anonymous namespace
+
+std::unique_ptr<SingletonHwndHotKeyObserver>
+SingletonHwndHotKeyObserver::Create(
+    const SingletonHwndObserver::WndProc& wnd_proc,
+    UINT key_code,
+    int modifiers) {
+  base::Optional<int> hot_key_id = GetAvailableHotKeyID();
+
+  // If there are no available hot key IDs, return null.
+  if (!hot_key_id.has_value())
+    return nullptr;
+
+  // If we fail to register the hot key, return null. Most likely reason for
+  // failure is that another application has already registered the hot key.
+  if (!RegisterHotKey(gfx::SingletonHwnd::GetInstance()->hwnd(), *hot_key_id,
+                      modifiers, key_code)) {
+    return nullptr;
+  }
+
+  return base::WrapUnique(
+      new SingletonHwndHotKeyObserver(wnd_proc, *hot_key_id));
+}
+
+SingletonHwndHotKeyObserver::SingletonHwndHotKeyObserver(
+    const SingletonHwndObserver::WndProc& wnd_proc,
+    int hot_key_id)
+    : observer_(base::BindRepeating(&SingletonHwndHotKeyObserver::OnWndProc,
+                                    base::Unretained(this))),
+      wnd_proc_(wnd_proc),
+      hot_key_id_(hot_key_id) {
+  SetHotKeyIDUsed(hot_key_id);
+}
+
+SingletonHwndHotKeyObserver::~SingletonHwndHotKeyObserver() {
+  bool success = !!UnregisterHotKey(gfx::SingletonHwnd::GetInstance()->hwnd(),
+                                    hot_key_id_);
+  // This call should always succeed, as long as we pass in the right HWND and
+  // an id we've used to register before.
+  DCHECK(success);
+  SetHotKeyIDAvailable(hot_key_id_);
+}
+
+void SingletonHwndHotKeyObserver::OnWndProc(HWND hwnd,
+                                            UINT message,
+                                            WPARAM wparam,
+                                            LPARAM lparam) {
+  // Only propagate WM_HOTKEY messages for this particular hot key to the owner
+  // of this observer.
+  if (message == WM_HOTKEY && static_cast<int>(wparam) == hot_key_id_)
+    wnd_proc_.Run(hwnd, message, wparam, lparam);
+}
+
+}  // namespace gfx