Adding key press detection in the browser process.

It works like this on the browser side: 
A new object UserInputMonitor is created on BrowserMainLoop and passed to AudioInputRendererHost to pass to AudioInputController.
AudioInputController::DoRecord calls UserInputMonitor::AddKeyStrokeListener --> UserInputMonitor listens to system key events (only implemented on Linux) --> AudioInputController::OnKeyPressed is called and sets key_pressed_ --> When AudioInputController::OnData called, it writes key_pressed_ to shared memory along with the audio data buffer.
On the renderer side a new param "key_pressed" is added through the code path of passing the flag to the webrtc voice engine.
This CL includes all these changes except the implementation of UserInputMonitor for Windows and Mac. The impl of UserInputMonitor is mostly copied from remoting/host/local_input_monitor_linux.cc


BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=217768

Review URL: https://chromiumcodereview.appspot.com/21183002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@217844 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 16 insertions, 0 deletions

diff --git a/media/base/user_input_monitor_win.cc b/media/base/user_input_monitor_win.cc
new file mode 100644
index 0000000..4ffad42
--- /dev/null
+++ b/media/base/user_input_monitor_win.cc
@@ -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