WebGL: Transfer ownership of WebGraphicsContext3D from WebGLRenderingContext to DrawingBuffer.

Source/core/html/canvas/WebGLRenderingContextBase.h

Index: Source/core/html/canvas/WebGLRenderingContextBase.h
diff --git a/Source/core/html/canvas/WebGLRenderingContextBase.h b/Source/core/html/canvas/WebGLRenderingContextBase.h
index c0ca96c1a8492a05cd07db547725006a9013fad4..3d755798890659c3d0fa6d5433f54f0cacd4558a 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.h
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.h
@@ -204,7 +204,7 @@ public:
 
     void hint(GLenum target, GLenum mode);
     GLboolean isBuffer(WebGLBuffer*);
-    bool isContextLost();
+    bool isContextLost() const;
     GLboolean isEnabled(GLenum cap);
     GLboolean isFramebuffer(WebGLFramebuffer*);
     GLboolean isProgram(WebGLProgram*);
@@ -323,7 +323,7 @@ public:
     void forceRestoreContext();
     void loseContextImpl(LostContextMode);
 
-    blink::WebGraphicsContext3D* webGraphicsContext3D() const { return m_context.get(); }
+    blink::WebGraphicsContext3D* webGraphicsContext3D() const;
     WebGLContextGroup* contextGroup() const { return m_contextGroup.get(); }
     virtual blink::WebLayer* platformLayer() const OVERRIDE;
     Extensions3DUtil* extensionsUtil();
@@ -390,12 +390,10 @@ protected:
 
     WebGLRenderbuffer* ensureEmulatedStencilBuffer(GLenum target, WebGLRenderbuffer*);
 
-    OwnPtr<blink::WebGraphicsContext3D> m_context;
-    RefPtr<WebGLContextGroup> m_contextGroup;
-
     // Structure for rendering to a DrawingBuffer, instead of directly
     // to the back-buffer of m_context.
     RefPtr<DrawingBuffer> m_drawingBuffer;
+    RefPtr<WebGLContextGroup> m_contextGroup;
 
     // Dispatches a context lost event once it is determined that one is needed.
     // This is used both for synthetic and real context losses. For real ones, it's