Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/html/canvas/CanvasRenderingContext.h

 /*
  * Copyright (C) 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 COMPUTER, 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 COMPUTER, 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 CanvasRenderingContext_h
 #define CanvasRenderingContext_h
 
 #include "core/html/HTMLCanvasElement.h"
+#include "platform/heap/Handle.h"
 #include "wtf/HashSet.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/text/StringHash.h"
 
 namespace blink { class WebLayer; }
 
 namespace WebCore {
 
 class HTMLCanvasElement;
 class KURL;
 class WebGLObject;
 
-class CanvasRenderingContext {
-    WTF_MAKE_NONCOPYABLE(CanvasRenderingContext); WTF_MAKE_FAST_ALLOCATED;
+class CanvasRenderingContext : public NoBaseWillBeGarbageCollectedFinalized<CanvasRenderingContext> {
+    WTF_MAKE_NONCOPYABLE(CanvasRenderingContext);
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
     virtual ~CanvasRenderingContext() { }
 
+#if !ENABLE(OILPAN)
     void ref() { m_canvas->ref(); }
     void deref() { m_canvas->deref(); }
+#endif
+
     HTMLCanvasElement* canvas() const { return m_canvas; }
 
     virtual bool is2d() const { return false; }
     virtual bool is3d() const { return false; }
     virtual bool isAccelerated() const { return false; }
     virtual bool hasAlpha() const { return true; }
 
     virtual void paintRenderingResultsToCanvas() {}
 
     virtual blink::WebLayer* platformLayer() const { return 0; }
+
+    virtual void trace(Visitor* visitor) { visitor->trace(m_canvas); }
+
 protected:
     CanvasRenderingContext(HTMLCanvasElement*);
 
 private:
-    HTMLCanvasElement* m_canvas;
+    RawPtrWillBeMember<HTMLCanvasElement> m_canvas;
 };
 
 } // namespace WebCore
 
 #endif