Move the Widget hierarchy to the Oilpan heap.

Source/platform/scroll/Scrollbar.h

 /*
  * Copyright (C) 2004, 2006 Apple Computer, 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 10 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef Scrollbar_h
 #define Scrollbar_h
 
 #include "platform/Timer.h"
 #include "platform/Widget.h"
+#include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/scroll/ScrollbarThemeClient.h"
 #include "wtf/MathExtras.h"
 #include "wtf/PassRefPtr.h"
 
 namespace blink {
 
 class GraphicsContext;
 class IntRect;
 class PlatformGestureEvent;
 class PlatformMouseEvent;
+class ScrollAnimator;
 class ScrollableArea;
 class ScrollbarTheme;
 
-class PLATFORM_EXPORT Scrollbar : public Widget,
-                  public ScrollbarThemeClient {
+class PLATFORM_EXPORT Scrollbar : public Widget, public ScrollbarThemeClient {
 
 public:
-    static PassRefPtr<Scrollbar> create(ScrollableArea*, ScrollbarOrientation, ScrollbarControlSize);
+    static PassRefPtrWillBeRawPtr<Scrollbar> create(ScrollableArea*, ScrollbarOrientation, ScrollbarControlSize);
 
     virtual ~Scrollbar();
 
     // ScrollbarThemeClient implementation.
     virtual int x() const override { return Widget::x(); }
     virtual int y() const override { return Widget::y(); }
     virtual int width() const override { return Widget::width(); }
     virtual int height() const override { return Widget::height(); }
     virtual IntSize size() const override { return Widget::size(); }
     virtual IntPoint location() const override { return Widget::location(); }
@@ skipping 29 matching lines @@
     virtual ScrollbarPart hoveredPart() const override { return m_hoveredPart; }
 
     virtual void styleChanged() override { }
 
     virtual bool enabled() const override { return m_enabled; }
     virtual void setEnabled(bool) override;
 
     // Called by the ScrollableArea when the scroll offset changes.
     void offsetDidChange();
 
-    void disconnectFromScrollableArea() { m_scrollableArea = 0; }
+    void disconnectFromScrollableArea();
     ScrollableArea* scrollableArea() const { return m_scrollableArea; }
 
     int pressedPos() const { return m_pressedPos; }
 
     virtual void setHoveredPart(ScrollbarPart);
     virtual void setPressedPart(ScrollbarPart);
 
     void setProportion(int visibleSize, int totalSize);
     void setPressedPos(int p) { m_pressedPos = p; }
 
@@ skipping 48 matching lines @@
     void stopTimerIfNeeded();
     void autoscrollPressedPart(double delay);
     ScrollDirection pressedPartScrollDirection();
     ScrollGranularity pressedPartScrollGranularity();
 
     ScrollableArea* m_scrollableArea;
     ScrollbarOrientation m_orientation;
     ScrollbarControlSize m_controlSize;
     ScrollbarTheme* m_theme;
 
+#if ENABLE(OILPAN)
+    // To simplify Oilpan finalization, keep a copy of the ScrollableArea's
+    // scroll animator. Scrollbar is responsible for notifying the animator
+    // when it is destructed.
+    RefPtr<ScrollAnimator> m_animator;
+#endif
+
     int m_visibleSize;
     int m_totalSize;
     float m_currentPos;
     float m_dragOrigin;
 
     ScrollbarPart m_hoveredPart;
     ScrollbarPart m_pressedPart;
     int m_pressedPos;
     float m_scrollPos;
     bool m_draggingDocument;
@@ skipping 12 matching lines @@
     virtual bool isScrollbar() const override { return true; }
 
     float scrollableAreaCurrentPos() const;
 };
 
 DEFINE_TYPE_CASTS(Scrollbar, Widget, widget, widget->isScrollbar(), widget.isScrollbar());
 
 } // namespace blink
 
 #endif // Scrollbar_h