Add watch time metrics for HTML5 media playback.

media/base/media_log.h

 // Copyright (c) 2012 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_MEDIA_LOG_H_
 #define MEDIA_BASE_MEDIA_LOG_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 65 matching lines @@
       int64_t end);
 
   // Report a log message at the specified log level.
   void AddLogEvent(MediaLogLevel level, const std::string& message);
 
   // Report a property change without an accompanying event.
   void SetStringProperty(const std::string& key, const std::string& value);
   void SetDoubleProperty(const std::string& key, double value);
   void SetBooleanProperty(const std::string& key, bool value);
 
+  // Histogram names used for reporting; also double as MediaLog key names.
+  static const char kWatchTimeAudioVideoAll[];
+  static const char kWatchTimeAudioVideoMse[];
+  static const char kWatchTimeAudioVideoEme[];
+  static const char kWatchTimeAudioVideoSrc[];
+  static const char kWatchTimeAudioVideoBattery[];
+  static const char kWatchTimeAudioVideoAc[];
+
+  // Markers which signify the watch time should be finalized immediately.
+  static const char kWatchTimeFinalize[];
+  static const char kWatchTimeFinalizePower[];
+
  protected:
   friend class base::RefCountedThreadSafe<MediaLog>;
   virtual ~MediaLog();
 
  private:
   // A unique (to this process) id for this MediaLog.
   int32_t id_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaLog);
 };
@@ skipping 34 matching lines @@
 #define LIMITED_MEDIA_LOG(level, media_log, count, max)                       \
   LAZY_STREAM(MEDIA_LOG(level, media_log),                                    \
               (count) < (max) && ((count)++ || true))                         \
       << (((count) == (max)) ? "(Log limit reached. Further similar entries " \
                                "may be suppressed): "                         \
                              : "")
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MEDIA_LOG_H_