Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 46 matching lines @@
 class CanvasObserver {
 public:
     virtual ~CanvasObserver() { }
 
     virtual void canvasChanged(HTMLCanvasElement*, const FloatRect& changedRect) = 0;
     virtual void canvasResized(HTMLCanvasElement*) = 0;
     virtual void canvasDestroyed(HTMLCanvasElement*) = 0;
 };
 
 class HTMLCanvasElement FINAL : public HTMLElement, public DocumentVisibilityObserver, public CanvasImageSource, public ImageBufferClient {
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLCanvasElement);
 public:
     static PassRefPtr<HTMLCanvasElement> create(Document&);
     virtual ~HTMLCanvasElement();
 
     void addObserver(CanvasObserver*);
     void removeObserver(CanvasObserver*);
 
     // Attributes and functions exposed to script
     int width() const { return size().width(); }
     int height() const { return size().height(); }
@@ skipping 61 matching lines @@
     virtual void didChangeVisibilityState(PageVisibilityState) OVERRIDE;
 
     // CanvasImageSource implementation
     virtual PassRefPtr<Image> getSourceImageForCanvas(SourceImageMode, SourceImageStatus*) const OVERRIDE;
     virtual bool wouldTaintOrigin(SecurityOrigin*) const OVERRIDE;
     virtual FloatSize sourceSize() const OVERRIDE;
 
     // ImageBufferClient implementation
     virtual void notifySurfaceInvalid() OVERRIDE;
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 protected:
     virtual void didMoveToNewDocument(Document& oldDocument) OVERRIDE;
 
 private:
     explicit HTMLCanvasElement(Document&);
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual RenderObject* createRenderer(RenderStyle*) OVERRIDE;
     virtual bool areAuthorShadowsAllowed() const OVERRIDE { return false; }
 
     void reset();
 
     PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
     void createImageBuffer();
     void createImageBufferInternal();
     void clearImageBuffer();
 
     void setSurfaceSize(const IntSize&);
 
     bool paintsIntoCanvasBuffer() const;
 
     void updateExternallyAllocatedMemory() const;
 
     HashSet<CanvasObserver*> m_observers;
 
     IntSize m_size;
 
-    OwnPtr<CanvasRenderingContext> m_context;
+    OwnPtrWillBeMember<CanvasRenderingContext> m_context;
 
     bool m_rendererIsCanvas;
 
     bool m_ignoreReset;
     bool m_accelerationDisabled;
     FloatRect m_dirtyRect;
 
     mutable intptr_t m_externallyAllocatedMemory;
 
     bool m_originClean;
 
     // It prevents HTMLCanvasElement::buffer() from continuously re-attempting to allocate an imageBuffer
     // after the first attempt failed.
     mutable bool m_didFailToCreateImageBuffer;
     mutable bool m_didClearImageBuffer;
     OwnPtr<ImageBuffer> m_imageBuffer;
     mutable OwnPtr<GraphicsContextStateSaver> m_contextStateSaver;
 
     mutable RefPtr<Image> m_presentedImage;
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } //namespace
 
 #endif