Avoid conditional Animation prefinalizers.

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

 /*
  * 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 44 matching lines @@
 class ExceptionState;
 class TreeScope;
 
 class CORE_EXPORT Animation final : public EventTargetWithInlineData,
                                     public ActiveScriptWrappable,
                                     public SuspendableObject,
                                     public CompositorAnimationDelegate,
                                     public CompositorAnimationPlayerClient {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(Animation);
-  USING_PRE_FINALIZER(Animation, dispose);
 
  public:
   enum AnimationPlayState { Unset, Idle, Pending, Running, Paused, Finished };
 
   static Animation* create(AnimationEffectReadOnly*, AnimationTimeline*);
   ~Animation();
   void dispose();
 
   // Returns whether the animation is finished.
   bool update(TimingUpdateReason);
@@ skipping 79 matching lines @@
   bool maybeStartAnimationOnCompositor();
   void cancelAnimationOnCompositor();
   void restartAnimationOnCompositor();
   void cancelIncompatibleAnimationsOnCompositor();
   bool hasActiveAnimationsOnCompositor();
   void setCompositorPending(bool effectChanged = false);
   void notifyCompositorStartTime(double timelineTime);
   void notifyStartTime(double timelineTime);
   // CompositorAnimationPlayerClient implementation.
   CompositorAnimationPlayer* compositorPlayer() const override {
-    return m_compositorPlayer.get();
+    return m_compositorPlayer ? m_compositorPlayer->player() : nullptr;
   }
 
   bool affects(const Element&, CSSPropertyID) const;
 
   // Returns whether we should continue with the commit for this animation or
   // wait until next commit.
   bool preCommit(int compositorGroup, bool startOnCompositor);
   void postCommit(double timelineTime);
 
   unsigned sequenceNumber() const { return m_sequenceNumber; }
@@ skipping 117 matching lines @@
                          TimingUpdateReason,
                          CompositorPendingChange = SetCompositorPending);
     ~PlayStateUpdateScope();
 
    private:
     Member<Animation> m_animation;
     AnimationPlayState m_initialPlayState;
     CompositorPendingChange m_compositorPendingChange;
   };
 
+  // CompositorAnimationPlayer objects need to eagerly sever
+  // their connection to their Animation delegate; use a separate
+  // 'holder' on-heap object to accomplish that.
+  class CompositorAnimationPlayerHolder
+      : public GarbageCollectedFinalized<CompositorAnimationPlayerHolder> {
+    USING_PRE_FINALIZER(CompositorAnimationPlayerHolder, dispose);
+
+   public:
+    static CompositorAnimationPlayerHolder* create(Animation*);
+
+    void detach();
+
+    DEFINE_INLINE_TRACE() { visitor->trace(m_animation); }
+
+    CompositorAnimationPlayer* player() const {
+      return m_compositorPlayer.get();
+    }
+
+   private:
+    explicit CompositorAnimationPlayerHolder(Animation*);
+
+    void dispose();
+
+    std::unique_ptr<CompositorAnimationPlayer> m_compositorPlayer;
+    Member<Animation> m_animation;
+  };
+
   // This mirrors the known compositor state. It is created when a compositor
   // animation is started. Updated once the start time is known and each time
   // modifications are pushed to the compositor.
   std::unique_ptr<CompositorState> m_compositorState;
   bool m_compositorPending;
   int m_compositorGroup;
 
-  std::unique_ptr<CompositorAnimationPlayer> m_compositorPlayer;
-  bool m_preFinalizerRegistered;
+  Member<CompositorAnimationPlayerHolder> m_compositorPlayer;
 
   bool m_currentTimePending;
   bool m_stateIsBeingUpdated;
 
   bool m_effectSuppressed;
 };
 
 }  // namespace blink
 
 #endif  // Animation_h