Attempt to fix the crash in blink Scroll Animator.

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 77 matching lines @@
 {
 }
 
 ScrollableArea::~ScrollableArea()
 {
 }
 
 void ScrollableArea::clearScrollAnimators()
 {
 #if OS(MACOSX) && ENABLE(OILPAN)
+    // TODO(ymalik): Let oilpan decide when to call dispose rather than
+    // explicitly calling it here to cleanup.
     if (m_scrollAnimator)
         m_scrollAnimator->dispose();
 #endif
     m_scrollAnimator.clear();
     m_programmaticScrollAnimator.clear();
 }
 
 ScrollAnimatorBase& ScrollableArea::scrollAnimator() const
 {
     if (!m_scrollAnimator)
@@ skipping 499 matching lines @@
         std::max(0, size.height() - horizontalScrollbarHeight));
 }
 
 DEFINE_TRACE(ScrollableArea)
 {
     visitor->trace(m_scrollAnimator);
     visitor->trace(m_programmaticScrollAnimator);
 }
 
 } // namespace blink