Add MediaStreamSource frame rate calculation to the tracker.

content/renderer/media/peer_connection_tracker.h

Index: content/renderer/media/peer_connection_tracker.h
diff --git a/content/renderer/media/peer_connection_tracker.h b/content/renderer/media/peer_connection_tracker.h
index 8a774cb7530f1ac7a710ddd954647a637a18ba72..6f453b9d81d93dc277cf9d6f241a2a236b1c6d73 100644
--- a/content/renderer/media/peer_connection_tracker.h
+++ b/content/renderer/media/peer_connection_tracker.h
@@ -155,6 +155,10 @@ class CONTENT_EXPORT PeerConnectionTracker : public RenderProcessObserver {
   virtual void TrackGetUserMedia(
       const blink::WebUserMediaRequest& user_media_request);
 
+  virtual void TrackAddVideoStats(const std::string& video_id,
+                                  float input_frate_rate,
+                                  int number_of_dropped_frames);
+
  private:
   // Assign a local ID to a peer connection so that the browser process can
   // uniquely identify a peer connection in the renderer process.