[Cast] Compute utilization metrics and add performance overlay.

media/cast/sender/video_sender.h

Index: media/cast/sender/video_sender.h
diff --git a/media/cast/sender/video_sender.h b/media/cast/sender/video_sender.h
index 386ddb9c7626cd8c221f31d80feeffc7278ff03e..f9b49e23322b1b107e47b466eaf7d5e8bf95373c 100644
--- a/media/cast/sender/video_sender.h
+++ b/media/cast/sender/video_sender.h
@@ -23,6 +23,7 @@ class VideoFrame;
 namespace cast {
 
 class CastTransportSender;
+struct SenderEncodedFrame;
 class VideoEncoder;
 class VideoFrameFactory;
 
@@ -67,7 +68,7 @@ class VideoSender : public FrameSender,
  private:
   // Called by the |video_encoder_| with the next EncodedFrame to send.
   void OnEncodedVideoFrame(int encoder_bitrate,
-                           scoped_ptr<EncodedFrame> encoded_frame);
+                           scoped_ptr<SenderEncodedFrame> encoded_frame);
 
   // Encodes media::VideoFrame images into EncodedFrames.  Per configuration,
   // this will point to either the internal software-based encoder or a proxy to
@@ -90,6 +91,12 @@ class VideoSender : public FrameSender,
 
   PlayoutDelayChangeCB playout_delay_change_cb_;
 
+  // The video encoder's performance metrics as of the last call to
+  // OnEncodedVideoFrame().  See header file comments for SenderEncodedFrame for
+  // an explanation of these values.
+  double last_reported_deadline_utilization_;
+  double last_reported_lossy_utilization_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<VideoSender> weak_factory_;