Add watch time metrics for HTML5 media playback.

media/base/media_log_event.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_EVENT_H_
 #define MEDIA_BASE_MEDIA_LOG_EVENT_H_
 
 #include <stdint.h>
 #include <memory>
 
@@ skipping 77 matching lines @@
     MEDIA_INFO_LOG_ENTRY,
     // params: "info": String with details of an informative log entry.
 
     // Debug log reported by media code.
     MEDIA_DEBUG_LOG_ENTRY,
     // params: "debug": String with details of a debug log entry.
 
     // A property has changed without any special event occurring.
     PROPERTY_CHANGE,
 
-    TYPE_LAST = PROPERTY_CHANGE
+    // Indicates that updated watch time statistics are available.
+    WATCH_TIME_UPDATE,
+
+    TYPE_LAST = WATCH_TIME_UPDATE
   };
 
   int32_t id;
   Type type;
   base::DictionaryValue params;
   base::TimeTicks time;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MEDIA_LOG_EVENT_H_