Revert 217768 "Adding key press detection in the browser process."

Revert 217768 "Adding key press detection in the browser process."

> Adding key press detection in the browser process.
> It works like this on the browser side: 
> A new object KeyPressMonitor is created on BrowserMainLoop and passed to AudioInputRendererHost to pass to AudioInputController.
> AudioInputController::DoRecord calls KeyPressMonitor::AddKeyPressListener --> KeyPressMonitor listens to system key events through UserInputMonitor(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=
> 
> Review URL: https://chromiumcodereview.appspot.com/21183002

TBR=jiayl@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=217774

[phoglund_chromium, 2013-08-15 11:11:38]

Committed patchset #1 manually as r217774.