[Chromecast] Add metrics for logging platform A/V bitrate estimates.

chromecast/media/cma/pipeline/video_pipeline_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromecast/media/cma/pipeline/video_pipeline_impl.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 99 matching lines @@
   current_stats.video_frames_dropped = video_stats.dropped_frames;
 
   ::media::PipelineStatistics delta_stats;
   delta_stats.video_bytes_decoded =
       current_stats.video_bytes_decoded - previous_stats_.video_bytes_decoded;
   delta_stats.video_frames_decoded =
       current_stats.video_frames_decoded - previous_stats_.video_frames_decoded;
   delta_stats.video_frames_dropped =
       current_stats.video_frames_dropped - previous_stats_.video_frames_dropped;
 
+  bytes_decoded_since_last_update_ = delta_stats.video_bytes_decoded;
   previous_stats_ = current_stats;
 
   client().statistics_cb.Run(delta_stats);
 }
 
 }  // namespace media
 }  // namespace chromecast