Add MediaStreamSource frame rate calculation to the tracker.

content/renderer/media/video_track_adapter.h

Index: content/renderer/media/video_track_adapter.h
diff --git a/content/renderer/media/video_track_adapter.h b/content/renderer/media/video_track_adapter.h
index 1a616126985bd16831e69b161f6d919fa0d6b983..e71d3d6cf110331c478a2d383dbf10d97487eae4 100644
--- a/content/renderer/media/video_track_adapter.h
+++ b/content/renderer/media/video_track_adapter.h
@@ -6,6 +6,7 @@
 #define CONTENT_RENDERER_MEDIA_VIDEO_TRACK_ADAPTER_H_
 
 #include <vector>
+#include <queue>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ -27,7 +28,7 @@ namespace content {
 class VideoTrackAdapter
     : public base::RefCountedThreadSafe<VideoTrackAdapter> {
  public:
-  typedef base::Callback<void(bool mute_state)> OnMutedCallback;
+  typedef base::Callback<void(float framerate, int dropped_frames)> OnFrameRateCallback;
 
   explicit VideoTrackAdapter(
       const scoped_refptr<base::MessageLoopProxy>& io_message_loop);
@@ -62,13 +63,16 @@ class VideoTrackAdapter
   // |DeliverFrameOnIO| is called with a frame rate of |source_frame_rate|.
   // |on_muted_callback| is triggered on the main render thread.
   void StartFrameMonitoring(double source_frame_rate,
-                            const OnMutedCallback& on_muted_callback);
+                            const OnFrameRateCallback& on_muted_callback);
   void StopFrameMonitoring();
 
  private:
   virtual ~VideoTrackAdapter();
   friend class base::RefCountedThreadSafe<VideoTrackAdapter>;
 
+  typedef base::Callback<void(float framerate, int dropped_frames)>
+      FrameRateCallback;
+
   void AddTrackOnIO(
       const MediaStreamVideoTrack* track,
       VideoCaptureDeliverFrameCB frame_callback,
@@ -79,14 +83,18 @@ class VideoTrackAdapter
   void RemoveTrackOnIO(const MediaStreamVideoTrack* track);
 
   void StartFrameMonitoringOnIO(
-    const OnMutedCallback& on_muted_state_callback,
+    const OnFrameRateCallback& on_muted_state_callback,
     double source_frame_rate);
   void StopFrameMonitoringOnIO();
 
   // Compare |frame_counter_snapshot| with the current |frame_counter_|, and
   // inform of the situation (muted, not muted) via |set_muted_state_callback|.
-  void CheckFramesReceivedOnIO(const OnMutedCallback& set_muted_state_callback,
-                               uint64 old_frame_counter_snapshot);
+  void CheckFramesReceivedOnIO(const OnFrameRateCallback& set_muted_state_callback,
+                               uint64 old_frame_counter_snapshot,
+                               int old_dropped_frame_counter_snapshot);
+
+  void UpdateFrameRateOnIO(base::TimeDelta timestamp);
+  float GetFrameRateOnIO();
 
   // |thread_checker_| is bound to the main render thread.
   base::ThreadChecker thread_checker_;
@@ -119,6 +127,9 @@ class VideoTrackAdapter
   // Frame rate configured on the video source, accessed on the IO-thread.
   float source_frame_rate_;
 
+  int dropped_frames_counter_;
+  std::queue<base::TimeDelta> frame_timestamps_;
+
   DISALLOW_COPY_AND_ASSIGN(VideoTrackAdapter);
 };