Using wrapWeakPersistent for VisibilityCallback in HTMLMediaElement

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1620 matching lines @@
             // If the autoplay experiment says that it's okay to play now,
             // then don't require a user gesture.
             m_autoplayHelper->becameReadyToPlay();
 
             if (!isGestureNeededForPlayback()) {
                 if (isHTMLVideoElement() && muted() && RuntimeEnabledFeatures::autoplayMutedVideosEnabled()) {
                     // We might end up in a situation where the previous
                     // observer didn't had time to fire yet. We can avoid
                     // creating a new one in this case.
                     if (!m_autoplayVisibilityObserver) {
-                        m_autoplayVisibilityObserver = new ElementVisibilityObserver(this, WTF::bind(&HTMLMediaElement::onVisibilityChangedForAutoplay, wrapPersistent(this)));
+                        m_autoplayVisibilityObserver = new ElementVisibilityObserver(this, WTF::bind(&HTMLMediaElement::onVisibilityChangedForAutoplay, wrapWeakPersistent(this)));
                         m_autoplayVisibilityObserver->start();
                     }
                 } else {
                     m_paused = false;
                     invalidateCachedTime();
                     scheduleEvent(EventTypeNames::play);
                     scheduleNotifyPlaying();
                     m_autoplaying = false;
                 }
             }
@@ skipping 2264 matching lines @@
     if (shouldAutoplay()) {
         m_paused = false;
         invalidateCachedTime();
         scheduleEvent(EventTypeNames::play);
         scheduleNotifyPlaying();
         m_autoplaying = false;
 
         updatePlayState();
     }
 
+    // TODO(zqzhang): There's still flaky leak if onVisibilityChangedForAutoplay() is never called.
+    // The leak comes from either ElementVisibilityObserver or IntersectionObserver. Should keep an eye on it.
+    // See https://crbug.com/627539
     m_autoplayVisibilityObserver->stop();
     m_autoplayVisibilityObserver = nullptr;
 }
 
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!ThreadHeap::isHeapObjectAlive(m_audioSourceNode)) {
         getAudioSourceProvider().setClient(nullptr);
         m_audioSourceNode = nullptr;
     }
@@ skipping 97 matching lines @@
 
 IntRect HTMLMediaElement::AutoplayHelperClientImpl::absoluteBoundingBoxRect() const
 {
     IntRect result;
     if (LayoutObject* object = m_element->layoutObject())
         result = object->absoluteBoundingBoxRect();
     return result;
 }
 
 } // namespace blink