Use NTP time for video frame timestamp. Add tracing for timestamps.

content/renderer/media/rtc_video_capturer.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_RTC_VIDEO_CAPTURER_H_
 #define CONTENT_RENDERER_MEDIA_RTC_VIDEO_CAPTURER_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 33 matching lines @@
   virtual void OnFrameCaptured(
       const media::VideoCapture::VideoFrameBuffer& frame);
 
   // State change callback, must be called on same thread as Start is called.
   void OnStateChange(RtcVideoCaptureDelegate::CaptureState state);
 
   const bool is_screencast_;
   scoped_refptr<RtcVideoCaptureDelegate> delegate_;
   VideoCaptureState state_;
   base::Time start_time_;
+  base::Time ntp_epoch_;
 
   DISALLOW_COPY_AND_ASSIGN(RtcVideoCapturer);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_RTC_VIDEO_CAPTURER_H_