Safely finalize an AnimationTimeline's still-attached Animations.

third_party/WebKit/Source/core/animation/Animation.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 93 matching lines @@
             m_content->animation()->cancel();
             m_content->animation()->setEffect(0);
         }
         m_content->attach(this);
     }
     InspectorInstrumentation::didCreateAnimation(m_timeline->document(), m_sequenceNumber);
 }
 
 Animation::~Animation()
 {
     destroyCompositorPlayer();

[haraken, 2015/12/09 14:02:04]

Can we remove this now?

[sof, 2015/12/09 14:04:33]

No, the AnimationTimeline keeps a weak reference to its animations. So Animation
objects may be swept independently. afaict.

 }
 
+void Animation::dispose()
+{
+    destroyCompositorPlayer();
+    // If the AnimationTimeline and its Animation objects are
+    // finalized by the same GC, we have to eagerly clear out
+    // this Animation object's compositor player registration.
+    ASSERT(!m_compositorPlayer);
+}
+
 double Animation::effectEnd() const
 {
     return m_content ? m_content->endTimeInternal() : 0;
 }
 
 bool Animation::limited(double currentTime) const
 {
     return (m_playbackRate < 0 && currentTime <= 0) || (m_playbackRate > 0 && currentTime >= effectEnd());
 }
 
@@ skipping 795 matching lines @@
     attachCompositedLayers();
 }
 
 void Animation::destroyCompositorPlayer()
 {
     detachCompositedLayers();
 
     if (m_compositorPlayer) {
         detachCompositorTimeline();
         m_compositorPlayer->setAnimationDelegate(nullptr);
+        m_compositorPlayer.clear();
     }
-    m_compositorPlayer.clear();
 }
 
 void Animation::attachCompositorTimeline()
 {
     if (m_compositorPlayer) {
         WebCompositorAnimationTimeline* timeline = m_timeline ? m_timeline->compositorTimeline() : nullptr;
         if (timeline)
             timeline->playerAttached(*this);
     }
 }
@@ skipping 143 matching lines @@
     visitor->trace(m_content);
     visitor->trace(m_timeline);
     visitor->trace(m_pendingFinishedEvent);
     visitor->trace(m_finishedPromise);
     visitor->trace(m_readyPromise);
     RefCountedGarbageCollectedEventTargetWithInlineData<Animation>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace