Notify ProgrammaticScrollAnimator about scroll layer destruction

Source/platform/scroll/ProgrammaticScrollAnimator.h

 // Copyright 2014 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 ProgrammaticScrollAnimator_h
 #define ProgrammaticScrollAnimator_h
 
 #include "platform/geometry/FloatPoint.h"
 #include "wtf/FastAllocBase.h"
 #include "wtf/Noncopyable.h"
@@ skipping 13 matching lines @@
 public:
     static PassOwnPtr<ProgrammaticScrollAnimator> create(ScrollableArea*);
 
     ~ProgrammaticScrollAnimator();
 
     void animateToOffset(FloatPoint);
     void cancelAnimation();
     void tickAnimation(double monotonicTime);
     bool hasAnimationThatRequiresService() const;
     void updateCompositorAnimations();
+    void layerForCompositedScrollingDidChange();
     void notifyCompositorAnimationFinished(int groupId);
 
 private:
     explicit ProgrammaticScrollAnimator(ScrollableArea*);
 
     enum class RunState {
         // No animation.
         Idle,
 
         // Waiting to send an animation to the compositor. There might also
@@ skipping 19 matching lines @@
     FloatPoint m_targetOffset;
     double m_startTime;
     RunState m_runState;
     int m_compositorAnimationId;
     int m_compositorAnimationGroupId;
 };
 
 } // namespace blink
 
 #endif // ProgrammaticScrollAnimator_h