Reland of Fix the video buffer size should take rtt into consideration

video/video_receive_stream.h

Index: video/video_receive_stream.h
diff --git a/video/video_receive_stream.h b/video/video_receive_stream.h
index 7a4a13e474221cc5a2f0d2a690b61746be99c085..b2eaa5e2e2fe29fb6e18ebad718cf41a0c8f1a27 100644
--- a/video/video_receive_stream.h
+++ b/video/video_receive_stream.h
@@ -50,7 +50,8 @@ class VideoReceiveStream : public webrtc::VideoReceiveStream,
                            public NackSender,
                            public KeyFrameRequestSender,
                            public video_coding::OnCompleteFrameCallback,
-                           public Syncable {
+                           public Syncable,
+                           public CallStatsObserver {
  public:
   VideoReceiveStream(RtpStreamReceiverControllerInterface* receiver_controller,
                      int num_cpu_cores,
@@ -103,6 +104,9 @@ class VideoReceiveStream : public webrtc::VideoReceiveStream,
   void OnCompleteFrame(
       std::unique_ptr<video_coding::FrameObject> frame) override;
 
+  // Implements CallStatsObserver::OnRttUpdate
+  void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) override;
+
   // Implements Syncable.
   int id() const override;
   rtc::Optional<Syncable::Info> GetInfo() const override;