Report video and network stats averaged over 1s, and create corresponding UMA metrics.

remoting/client/chromoting_stats.h

Index: remoting/client/chromoting_stats.h
diff --git a/remoting/client/chromoting_stats.h b/remoting/client/chromoting_stats.h
index da7601b7f9222d3026fe768713db067a8a4c0b78..28260349119e2008be2f98090562a23875a2e436 100644
--- a/remoting/client/chromoting_stats.h
+++ b/remoting/client/chromoting_stats.h
@@ -18,8 +18,27 @@ class ChromotingStats {
   ChromotingStats();
   virtual ~ChromotingStats();
 
+  // Constant used to calculate the average for rate metrics and used by the
+  // plugin for the frequency at which stats should be updated.
+  static const int kStatsUpdateFrequencyInSeconds = 1;
+
+  // The video and packet rate metrics below are updated per video packet
+  // received and then, for reporting, averaged over a 1s time-window.
+  // Bytes per second for non-empty video-packets.
   RateCounter* video_bandwidth() { return &video_bandwidth_; }
+
+  // Frames per second for non-empty video-packets.
   RateCounter* video_frame_rate() { return &video_frame_rate_; }
+
+  // Video packets per second, including empty video-packets.
+  // This will be greater than the frame rate, as individual frames are
+  // contained in packets, some of which might be empty (e.g. when there are no
+  // screen changes).
+  RateCounter* video_packet_rate() { return &video_packet_rate_; }
+
+  // The latency metrics below are recorded per video packet received and, for
+  // reporting, averaged over the N most recent samples.
+  // N is defined by kLatencySampleSize.
   RunningAverage* video_capture_ms() { return &video_capture_ms_; }
   RunningAverage* video_encode_ms() { return &video_encode_ms_; }
   RunningAverage* video_decode_ms() { return &video_decode_ms_; }
@@ -29,6 +48,7 @@ class ChromotingStats {
  private:
   RateCounter video_bandwidth_;
   RateCounter video_frame_rate_;
+  RateCounter video_packet_rate_;
   RunningAverage video_capture_ms_;
   RunningAverage video_encode_ms_;
   RunningAverage video_decode_ms_;