Eliminate use of cricket::VideoFrame::GetTimeStamp.

content/renderer/media/webrtc/media_stream_remote_video_source.cc

Index: content/renderer/media/webrtc/media_stream_remote_video_source.cc
diff --git a/content/renderer/media/webrtc/media_stream_remote_video_source.cc b/content/renderer/media/webrtc/media_stream_remote_video_source.cc
index 8f1e0751df92974e28f4f87f23a793ccef1f5ea8..b4d51585531804d7ce4d798de1b9794aa22458d8 100644
--- a/content/renderer/media/webrtc/media_stream_remote_video_source.cc
+++ b/content/renderer/media/webrtc/media_stream_remote_video_source.cc
@@ -98,7 +98,7 @@ void DoNothing(const scoped_refptr<rtc::RefCountInterface>& ref) {}
 void MediaStreamRemoteVideoSource::RemoteVideoSourceDelegate::OnFrame(
     const cricket::VideoFrame& incoming_frame) {
   const base::TimeDelta incoming_timestamp = base::TimeDelta::FromMicroseconds(
-      incoming_frame.GetTimeStamp() / rtc::kNumNanosecsPerMicrosec);
+      incoming_frame.timestamp_us());
   const base::TimeTicks render_time =
       base::TimeTicks() + incoming_timestamp + time_diff_;