Pass a TimeTicks along video capture pipeline to represent capture time

content/renderer/media/webrtc/media_stream_remote_video_source.cc

 // Copyright 2014 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 "content/renderer/media/webrtc/media_stream_remote_video_source.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 102 matching lines @@
       FROM_HERE,
       base::Bind(&RemoteVideoSourceDelegate::DoRenderFrameOnIOThread,
                  this, video_frame, format));
 }
 
 void MediaStreamRemoteVideoSource::
 RemoteVideoSourceDelegate::DoRenderFrameOnIOThread(
     scoped_refptr<media::VideoFrame> video_frame,
     const media::VideoCaptureFormat& format) {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
-  frame_callback_.Run(video_frame, format);
+  // We cannot estimate the local time when this frame is generated so give a
+  // null value to |estimated_capture_time|.

[Ronghua Wu (Left Chromium), 2014/06/02 18:09:09]

The comment is not accurate. We do have estimated capture time available in
underlying code. We just build an interface to expose it to here, e.g. via the
cricket::VideoFrame or and another filed to RenderFrame.

+  frame_callback_.Run(video_frame, format, base::TimeTicks());
 }
 
 MediaStreamRemoteVideoSource::MediaStreamRemoteVideoSource(
     webrtc::VideoTrackInterface* remote_track)
     : remote_track_(remote_track),
       last_state_(remote_track->state()) {
   remote_track_->RegisterObserver(this);
 }
 
 MediaStreamRemoteVideoSource::~MediaStreamRemoteVideoSource() {
@@ skipping 49 matching lines @@
         SetReadyState(blink::WebMediaStreamSource::ReadyStateEnded);
         break;
       default:
         NOTREACHED();
         break;
     }
   }
 }
 
 }  // namespace content