Added UMA metrics for MediaSourcePlayer and MediaCodecPlayer

media/base/android/media_statistics.h

Index: media/base/android/media_statistics.h
diff --git a/media/base/android/media_statistics.h b/media/base/android/media_statistics.h
new file mode 100644
index 0000000000000000000000000000000000000000..e8279851826f8679906200b8045f886bbf7137b9
--- /dev/null
+++ b/media/base/android/media_statistics.h
@@ -0,0 +1,59 @@
+// Copyright 2015 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.
+
+#ifndef MEDIA_BASE_ANDROID_MEDIA_STATISTICS_H_
+#define MEDIA_BASE_ANDROID_MEDIA_STATISTICS_H_
+
+#include <stdint.h>
+#include "base/time/time.h"
+#include "media/base/demuxer_stream.h"
+
+namespace media {
+
+// FrameStatistics struct deals with frames of one stream, i.e. either
+// audio or video.
+struct FrameStatistics {
+  DemuxerStream::Type stream_type;
+  uint32_t total;

[qinmin, 2015/09/29 23:47:44]

provide comments on these variables.

[Tima Vaisburd, 2015/09/30 18:50:10]

Done.

+  uint32_t late;
+
+  FrameStatistics(DemuxerStream::Type type)
+      : stream_type(type), total(0), late(0) {}
+
+  void Clear() { total = late = 0; }
+  void AddFrame();
+  void AddLateFrame(base::TimeDelta delay);
+};
+
+// MediaStatistics class gathers and reports playback quality statistics to UMA.
+//
+// This class is not thread safe. The caller should guarantee that operations
+// on FrameStatistics objects does not happen during Start() and
+// StopAndReport(). The Start() and StopAndReport() methods need to be called
+// sequantially.
+
+class MediaStatistics {
+ public:
+  MediaStatistics();
+  ~MediaStatistics();
+
+  FrameStatistics& AudioFrames() { return audio_frames_; }

[qinmin, 2015/09/29 23:47:44]

audio_frames();

[Tima Vaisburd, 2015/09/30 18:50:09]

Done.

+  FrameStatistics& VideoFrames() { return video_frames_; }

[qinmin, 2015/09/29 23:47:44]

video_frames()

[Tima Vaisburd, 2015/09/30 18:50:10]

Done.

+  void Start();

[qinmin, 2015/09/29 23:47:44]

comments on member functions

[Tima Vaisburd, 2015/09/30 18:50:09]

Done.

+  void AddStarvation();
+  void StopAndReport();
+
+ private:
+  void Clear();
+  void Report(base::TimeDelta duration);
+
+  base::TimeTicks start_time_;
+  FrameStatistics audio_frames_;
+  FrameStatistics video_frames_;
+  uint32_t num_starvations_;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_MEDIA_STATISTICS_H_