Adding key press detection in the browser process.

media/base/user_input_monitor_mac.mm

Index: media/base/user_input_monitor_mac.mm
diff --git a/media/base/user_input_monitor_mac.mm b/media/base/user_input_monitor_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..4ffad42a72d9b479d1611e4a10fea96ae41e0e5d
--- /dev/null
+++ b/media/base/user_input_monitor_mac.mm
@@ -0,0 +1,16 @@
+// Copyright 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/base/user_input_monitor.h"
+
+namespace media {
+
+// TODO(jiayl): add the implementation.
+scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
+    const scoped_refptr<base::SingleThreadTaskRunner>& input_task_runner,
+    const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner) {
+  return scoped_ptr<UserInputMonitor>();
+}
+
+}  // namespace media