Autoplay time metric

third_party/WebKit/Source/core/html/media/AutoplayUmaHelper.h

 // Copyright 2016 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 AutoplayUmaHelper_h
 #define AutoplayUmaHelper_h
 
 #include "core/CoreExport.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/events/EventListener.h"
@@ skipping 95 matching lines @@
 
   void OnVisibilityChangedForMutedVideoOffscreenDuration(bool is_visibile);
   void OnVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool is_visible);
 
   bool ShouldListenToContextDestroyed() const;
   bool ShouldRecordUserPausedAutoplayingCrossOriginVideo() const;
 
   // The autoplay sources.
   std::set<AutoplaySource> sources_;
 
-  // The media element this UMA helper is attached to. |m_element| owns |this|.
+  // The media element this UMA helper is attached to. |element| owns |this|.
   Member<HTMLMediaElement> element_;
 
   // The observer is used to observe whether a muted video autoplaying by play()
   // method become visible at some point.
   // The UMA is pending for recording as long as this observer is non-null.
   Member<ElementVisibilityObserver>
       muted_video_play_method_visibility_observer_;
 
   // -----------------------------------------------------------------------
   // Variables used for recording the duration of autoplay muted video playing
   // offscreen.  The variables are valid when
-  // |m_autoplayOffscrenVisibilityObserver| is non-null.
+  // |autoplayOffscrenVisibilityObserver| is non-null.
   // The recording stops whenever the playback pauses or the page is unloaded.
 
   // The starting time of autoplaying muted video.
   int64_t muted_video_autoplay_offscreen_start_time_ms_;
 
   // The duration an autoplaying muted video has been in offscreen.
   int64_t muted_video_autoplay_offscreen_duration_ms_;
 
   // Whether an autoplaying muted video is visible.
   bool is_visible_;
 
   std::set<CrossOriginAutoplayResult> recorded_cross_origin_autoplay_results_;
 
   // The observer is used to observer an autoplaying muted video changing it's
   // visibility, which is used for offscreen duration UMA.  The UMA is pending
   // for recording as long as this observer is non-null.
   Member<ElementVisibilityObserver>
       muted_video_offscreen_duration_visibility_observer_;
+
+  double created_time_ms_;

[Zhiqiang Zhang (Slow), 2017/05/02 00:12:05]

nit: maybe "creation_time_ms_" is better?

 };
 
 }  // namespace blink
 
 #endif  // AutoplayUmaHelper_h