Record the offscreen playing duration of autoplaying muted videos

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

Index: third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
diff --git a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
index edfca0b8d490f2fa15796a60997b9947d360f61d..05451433270e8d7cc3372be60a62bce694697199 100644
--- a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
@@ -43,8 +43,6 @@ public:
 
     void recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus);
 
-    void onVisibilityChangedForVideoMutedPlayMethod(bool isVisible);
-
     void didMoveToNewDocument(Document& oldDocument);
 
     DECLARE_VIRTUAL_TRACE();
@@ -55,14 +53,50 @@ private:
     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|.
     WeakMember<HTMLMediaElement> m_element;
-    // The observer is used to observe whether a muted video autoplaying by play() method become visible at some point.
-    Member<ElementVisibilityObserver> m_videoMutedPlayMethodVisibilityObserver;
+
+    // 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;
+
+    // -----------------------------------------------------------------------
+    // 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;
 };
 
 } // namespace blink