Implement first part of supporting global extension commands.

chrome/browser/extensions/global_shortcut_listener.cc

+// Copyright (c) 2013 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 "chrome/browser/extensions/global_shortcut_listener.h"
+#include "chrome/browser/profiles/profile.h"
+#include "ui/base/accelerators/accelerator.h"
+
+namespace extensions {
+
+GlobalShortcutListener::GlobalShortcutListener() {
+}
+
+GlobalShortcutListener::~GlobalShortcutListener() {
+  DCHECK(accelerator_map_.empty());  // Make sure we've cleaned up.
+}
+
+void GlobalShortcutListener::RegisterAccelerator(
+    const ui::Accelerator& accelerator, Observer* observer) {
+  AcceleratorMap::const_iterator it = accelerator_map_.find(accelerator);
+  if (it == accelerator_map_.end()) {
+    if (accelerator_map_.empty())
+      GlobalShortcutListener::GetInstance()->StartListening();
+    Observers* observers = new Observers;
+    observers->AddObserver(observer);
+    accelerator_map_[accelerator] = observers;
+  } else {
+    // Make sure we don't register the same accelerator twice.
+    DCHECK(!accelerator_map_[accelerator]->HasObserver(observer));
+    accelerator_map_[accelerator]->AddObserver(observer);
+  }
+}
+
+void GlobalShortcutListener::UnregisterAccelerator(
+    const ui::Accelerator& accelerator, Observer* observer) {
+  AcceleratorMap::iterator it = accelerator_map_.find(accelerator);
+  DCHECK(it != accelerator_map_.end());
+  DCHECK(it->second->HasObserver(observer));
+  it->second->RemoveObserver(observer);
+  if (!it->second->might_have_observers()) {
+    accelerator_map_.erase(it);
+    if (accelerator_map_.empty())
+      GlobalShortcutListener::GetInstance()->StopListening();
+  }
+}
+
+void GlobalShortcutListener::NotifyKeyPressed(
+    const ui::Accelerator& accelerator) {
+  AcceleratorMap::iterator iter = accelerator_map_.find(accelerator);
+  if (iter == accelerator_map_.end()) {
+    NOTREACHED();

[Yoyo Zhou, 2013/10/03 22:08:50]

If this is intended, the function comment should be clearer about when it's
expected to be called.

[Finnur, 2013/10/04 17:57:02]

Clarified.

+    return;  // No-one is listening to this key.
+  }
+  // The observer list should not be empty.
+  DCHECK(iter->second->might_have_observers());
+
+  FOR_EACH_OBSERVER(Observer, *(iter->second), OnKeyPressed(accelerator));
+}
+
+}  // namespace extensions