Merge 116476

Source/WebCore/rendering/RenderScrollbar.h

 /*
  * Copyright (C) 2008, 2009 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:
  * 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
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * 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 RenderScrollbar_h
 #define RenderScrollbar_h
 
+#include "Node.h"
 #include "RenderStyleConstants.h"
 #include "Scrollbar.h"
 #include <wtf/HashMap.h>
 
 namespace WebCore {
 
 class Frame;
 class RenderBox;
 class RenderScrollbarPart;
 class RenderStyle;
 
 class RenderScrollbar : public Scrollbar {
 protected:
-    RenderScrollbar(ScrollableArea*, ScrollbarOrientation, RenderBox*, Frame*);
+    RenderScrollbar(ScrollableArea*, ScrollbarOrientation, Node*, Frame*);
 
 public:
     friend class Scrollbar;
-    static PassRefPtr<Scrollbar> createCustomScrollbar(ScrollableArea*, ScrollbarOrientation, RenderBox*, Frame* owningFrame = 0);
+    static PassRefPtr<Scrollbar> createCustomScrollbar(ScrollableArea*, ScrollbarOrientation, Node*, Frame* owningFrame = 0);
     virtual ~RenderScrollbar();
 
     static ScrollbarPart partForStyleResolve();
     static RenderScrollbar* scrollbarForStyleResolve();
 
     RenderBox* owningRenderer() const;
-    void clearOwningRenderer() { m_owner = 0; }
 
     void paintPart(GraphicsContext*, ScrollbarPart, const IntRect&);
 
     IntRect buttonRect(ScrollbarPart);
     IntRect trackRect(int startLength, int endLength);
     IntRect trackPieceRectWithMargins(ScrollbarPart, const IntRect&);
 
     int minimumThumbLength();
 
     virtual bool isOverlayScrollbar() const { return false; }
 
 private:
     virtual void setParent(ScrollView*);
     virtual void setEnabled(bool);
 
     virtual void paint(GraphicsContext*, const IntRect& damageRect);
 
     virtual void setHoveredPart(ScrollbarPart);
     virtual void setPressedPart(ScrollbarPart);
 
     virtual void styleChanged();
 
     virtual bool isCustomScrollbar() const { return true; }
 
     void updateScrollbarParts(bool destroy = false);
 
     PassRefPtr<RenderStyle> getScrollbarPseudoStyle(ScrollbarPart, PseudoId);
     void updateScrollbarPart(ScrollbarPart, bool destroy = false);
 
-    RenderBox* m_owner;
+    // This Scrollbar(Widget) may outlive the DOM which created it (during tear down),
+    // so we keep a reference to the Node which caused this custom scrollbar creation.
+    // This will not create a reference cycle as the Widget tree is owned by our containing
+    // FrameView which this Node pointer can in no way keep alive. See webkit bug 80610.
+    RefPtr<Node> m_owner;
+
     Frame* m_owningFrame;
     HashMap<unsigned, RenderScrollbarPart*> m_parts;
 };
 
 inline RenderScrollbar* toRenderScrollbar(ScrollbarThemeClient* scrollbar)
 {
     ASSERT(!scrollbar || scrollbar->isCustomScrollbar());
     return static_cast<RenderScrollbar*>(scrollbar);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toRenderScrollbar(const RenderScrollbar*);
 
 } // namespace WebCore
 
 #endif // RenderScrollbar_h