Add an audio/video synchronization utility

On Chameleon, audio capturing and video capturing work separately.
To know the time difference between audio/video capturing, we can
monitor the changes of the audio page count and the video frame count.

TEST=manual test.
  Use test_server to test StartMonitoringAudioVideoCapturingDelay() and
  GetAudioVideoCapturingDelay(), note that the edid should be equipped
  with audio.
  >>> for i in xrange(10):
  ...   p.StartMonitoringAudioVideoCapturingDelay()
  ...   p.StartCapturingVideo(3)
  ...   p.StartCapturingAudio(3)
  ...   time.sleep(2)
  ...   p.StopCapturingVideo()
  ...   p.StopCapturingAudio(3)
  ...   print p.GetAudioVideoCapturingDelay()

Change-Id: I9b213964afed51a2e9c7b9c56ddc8b6002ef73bd
Commit-Ready: Chen-hao Chang <>
Tested-by: Chen-hao Chang <>
Reviewed-by: Wai-Hong Tam <>
5 files changed