Adding key press detection in the browser process.

media/audio/key_press_monitor.cc

Index: media/audio/key_press_monitor.cc
diff --git a/media/audio/key_press_monitor.cc b/media/audio/key_press_monitor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8b58727b4d83dca4cae8036547f1cfef1c2c83e0
--- /dev/null
+++ b/media/audio/key_press_monitor.cc
@@ -0,0 +1,23 @@
+// 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"
+
+namespace media {
+
+KeyPressMonitor::KeyPressMonitor() {}
+
+KeyPressMonitor::~KeyPressMonitor() {}
+
+void KeyPressMonitor::AddKeyPressListener(KeyPressListener* listener) {
+  base::AutoLock auto_lock(listeners_lock_);
+  listeners_.AddObserver(listener);
+}
+
+void KeyPressMonitor::RemoveKeyPressListener(KeyPressListener* listener) {
+  base::AutoLock auto_lock(listeners_lock_);
+  listeners_.RemoveObserver(listener);
+}
+
+}  // namespace media