Add cricket::VideoFrame::frame_id() and set it to RTP timestamp.

webrtc/media/base/videoframe.h

 /*
  *  Copyright (c) 2004 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 16 matching lines @@
   // Basic accessors.
   // Note this is the width and height without rotation applied.
   virtual int width() const = 0;
   virtual int height() const = 0;
 
   // Returns the underlying video frame buffer. This function is ok to call
   // multiple times, but the returned object will refer to the same memory.
   virtual const rtc::scoped_refptr<webrtc::VideoFrameBuffer>&
   video_frame_buffer() const = 0;
 
+  // Frame ID. Normally RTP timestamp when the frame was received using RTP.
+  virtual uint32_t frame_id() const = 0;

[stefan-webrtc, 2016/07/28 08:54:49]

Maybe add "transport" to the name to make it more clear that this is something
that only exists after the frame has been sent (or received) over the network
since it's set by the transport layer.

[Sergey Ulanov, 2016/07/29 00:10:22]

Done.

+
   // System monotonic clock, same timebase as rtc::TimeMicros().
   virtual int64_t timestamp_us() const = 0;
   virtual void set_timestamp_us(int64_t time_us) = 0;
 
   // Deprecated methods, for backwards compatibility.
   // TODO(nisse): Delete when usage in Chrome and other applications
   // have been replaced.
   virtual int64_t GetTimeStamp() const {
     return rtc::kNumNanosecsPerMicrosec * timestamp_us();
   }
@@ skipping 34 matching lines @@
   virtual VideoFrame* CreateEmptyFrame(int w,
                                        int h,
                                        int64_t timestamp_us) const = 0;
 
   virtual void set_rotation(webrtc::VideoRotation rotation) = 0;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_VIDEOFRAME_H_