Monitor the intersection of video and viewport.

third_party/WebKit/Source/core/html/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/events/EventListener.h"
 #include "platform/heap/Handle.h"
 
@@ skipping 19 matching lines @@
 // These values are used for histograms. Do not reorder.
 enum AutoplayBlockedReason {
   AutoplayBlockedReasonDataSaver = 0,
   AutoplayBlockedReasonSetting = 1,
   AutoplayBlockedReasonDataSaverAndSetting = 2,
   // Keey at the end.
   AutoplayBlockedReasonMax = 3
 };
 
 class Document;
 class ElementVisibilityObserver;

[Zhiqiang Zhang (Slow), 2016/11/15 11:29:27]

nit: remove this forward decl

[xjz, 2016/11/15 23:03:39]

Done.

 class HTMLMediaElement;
 
 class AutoplayUmaHelper final : public EventListener {
  public:
   static AutoplayUmaHelper* create(HTMLMediaElement*);
 
   ~AutoplayUmaHelper();
 
   bool operator==(const EventListener&) const override;
 
   void onAutoplayInitiated(AutoplaySource);
 
   void recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus);
 
   void didMoveToNewDocument(Document& oldDocument);
 
   bool isVisible() const { return m_isVisible; }
 
   bool hasSource() const { return m_source != AutoplaySource::NumberOfSources; }
 
+  void visibilityMaybeChangedforMutedVideo(bool isVisible);
+
   DECLARE_VIRTUAL_TRACE();
 
  private:
   explicit AutoplayUmaHelper(HTMLMediaElement*);
 
   void handleEvent(ExecutionContext*, Event*) override;
 
   void handlePlayingEvent();
   void handlePauseEvent();
   void handleUnloadEvent();
 
   void maybeUnregisterUnloadListener();
 
   void maybeStartRecordingMutedVideoPlayMethodBecomeVisible();
   void maybeStopRecordingMutedVideoPlayMethodBecomeVisible(bool isVisible);
 
   void maybeStartRecordingMutedVideoOffscreenDuration();
   void maybeStopRecordingMutedVideoOffscreenDuration();
 
-  void onVisibilityChangedForMutedVideoOffscreenDuration(bool isVisibile);
-  void onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool isVisible);
-
   bool shouldListenToUnloadEvent() const;
 
   // The autoplay source. Use AutoplaySource::NumberOfSources for invalid
   // source.
   AutoplaySource m_source;
   // The media element this UMA helper is attached to. |m_element| owns |this|.
   Member<HTMLMediaElement> m_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> m_mutedVideoPlayMethodVisibilityObserver;
+  // Indicates whether is observing the visibility of a muted video autoplayed
+  // from 'play()' method. The UMA is pending for recording as long as this is
+  // true.
+  bool m_isObservingVisibilityOfMutedAutoplayVideo = false;

[Zhiqiang Zhang (Slow), 2016/11/15 11:29:27]

nit: Currently, this is describing more than what we use it for.
You can rename it `m_isObservingMutedVideoPlayMethodBecomeVisible`, and change
the comment accordingly.

[xjz, 2016/11/15 23:03:39]

Done.

 
   // -----------------------------------------------------------------------
   // Variables used for recording the duration of autoplay muted video playing
   // offscreen.  The variables are valid when
   // |m_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 m_mutedVideoAutoplayOffscreenStartTimeMS;
 
   // The duration an autoplaying muted video has been in offscreen.
   int64_t m_mutedVideoAutoplayOffscreenDurationMS;
 
   // Whether an autoplaying muted video is visible.
   bool m_isVisible;
 
-  // 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>
-      m_mutedVideoOffscreenDurationVisibilityObserver;
+  // Indicates whether is observing the visibility of a muted autoplay video for
+  // offscreen duration UMA.  The UMA is pending for recording as long as this
+  // is true.
+  bool m_isObservingVisibilityOfMutedVideoOffscreenDuration = false;
 };
 
 }  // namespace blink
 
 #endif  // AutoplayUmaHelper_h