Reland of Change VideoTrack implementation to invoke VideoTrackSourceInterface::AddOrUpdateSink on …

webrtc/pc/rtcstatscollector_unittest.cc

 /*
  *  Copyright 2016 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 200 matching lines @@
     return video_track;
   }
 
   FakeVideoTrackForStats(const std::string& id)
       : MediaStreamTrack<VideoTrackInterface>(id) {
   }
 
   std::string kind() const override {
     return MediaStreamTrackInterface::kVideoKind;
   }
+
+  void AddOrUpdateSink(rtc::VideoSinkInterface<VideoFrame>* sink,
+                       const rtc::VideoSinkWants& wants) override{};
+  void RemoveSink(rtc::VideoSinkInterface<VideoFrame>* sink) override{};
+
   VideoTrackSourceInterface* GetSource() const override { return nullptr; }
 };
 
 rtc::scoped_refptr<MediaStreamTrackInterface> CreateFakeTrack(
     cricket::MediaType media_type,
     const std::string& track_id,
     MediaStreamTrackInterface::TrackState track_state) {
   if (media_type == cricket::MEDIA_TYPE_AUDIO) {
     return FakeAudioTrackForStats::Create(track_id, track_state);
   } else {
@@ skipping 2094 matching lines @@
   rtc::scoped_refptr<FakeRTCStatsCollector> collector_;
 };
 
 TEST_F(RTCStatsCollectorTestWithFakeCollector, ThreadUsageAndResultsMerging) {
   collector_->VerifyThreadUsageAndResultsMerging();
 }
 
 }  // namespace
 
 }  // namespace webrtc