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

webrtc/pc/rtcstatscollector_unittest.cc

Index: webrtc/pc/rtcstatscollector_unittest.cc
diff --git a/webrtc/pc/rtcstatscollector_unittest.cc b/webrtc/pc/rtcstatscollector_unittest.cc
index 8dc4a9702cdd0fd686fdbae5f237c3f351675985..f6591c0d66ec7530fc143a120efc7f69b4d5ca1d 100644
--- a/webrtc/pc/rtcstatscollector_unittest.cc
+++ b/webrtc/pc/rtcstatscollector_unittest.cc
@@ -218,6 +218,11 @@ class FakeVideoTrackForStats
   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; }
 };