Change PaintLayer::m_layoutObject to a reference.

third_party/WebKit/Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
    reserved.
 
    This library is free software; you can redistribute it and/or
@@ skipping 212 matching lines @@
   void adjustMediaTypeForPrinting(bool printing);
 
   WebDisplayMode displayMode() { return m_displayMode; }
   void setDisplayMode(WebDisplayMode);
 
   DisplayShape displayShape() { return m_displayShape; }
   void setDisplayShape(DisplayShape);
 
   // Fixed-position objects.
   typedef HashSet<LayoutObject*> ViewportConstrainedObjectSet;
-  void addViewportConstrainedObject(LayoutObject*);
-  void removeViewportConstrainedObject(LayoutObject*);
+  void addViewportConstrainedObject(LayoutObject&);
+  void removeViewportConstrainedObject(LayoutObject&);
   const ViewportConstrainedObjectSet* viewportConstrainedObjects() const {
     return m_viewportConstrainedObjects.get();
   }
   bool hasViewportConstrainedObjects() const {
     return m_viewportConstrainedObjects &&
            m_viewportConstrainedObjects->size() > 0;
   }
 
   // Objects with background-attachment:fixed.
   void addBackgroundAttachmentFixedObject(LayoutObject*);
@@ skipping 1006 matching lines @@
                   widget.isFrameView());
 DEFINE_TYPE_CASTS(FrameView,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->isFrameView(),
                   scrollableArea.isFrameView());
 
 }  // namespace blink
 
 #endif  // FrameView_h