Adding key press detection in the browser process.

media/audio/key_press_monitor.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 "media/audio/key_press_monitor.h"
+
+#include "base/message_loop/message_loop_proxy.h"
+
+namespace media {
+
+KeyPressMonitor::KeyPressMonitor(base::MessageLoopProxy* message_loop)

[DaleCurtis, 2013/08/02 21:04:47]

const scoped_refptr<base::MessageLoopProxy>&

[jiayl, 2013/08/02 21:45:45]

Done.

+    : message_loop_(message_loop) {}
+
+KeyPressMonitor::~KeyPressMonitor() {}
+
+void KeyPressMonitor::AddKeyPressListener(KeyPressListener* listener) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  listeners_.AddObserver(listener);
+}
+
+void KeyPressMonitor::RemoveKeyPressListener(KeyPressListener* listener) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  listeners_.RemoveObserver(listener);
+}
+
+}  // namespace media