Fixing Canvas2DLayerBridge to handle lost graphics contexts

Source/core/platform/graphics/chromium/Canvas2DLayerBridge.h

Index: Source/core/platform/graphics/chromium/Canvas2DLayerBridge.h
diff --git a/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.h b/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.h
index 510f479e5cd5dda6bfcee6c7e6c3576f1c0bafec..cfde606f26c15701f1cfe57ad4e8d5aebe94a734 100644
--- a/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.h
+++ b/Source/core/platform/graphics/chromium/Canvas2DLayerBridge.h
@@ -56,10 +56,7 @@ public:
         Threaded
     };
 
-    static PassOwnPtr<Canvas2DLayerBridge> create(PassRefPtr<GraphicsContext3D> context, SkDeferredCanvas* canvas, OpacityMode opacityMode, ThreadMode threading)
-    {
-        return adoptPtr(new Canvas2DLayerBridge(context, canvas, opacityMode, threading));
-    }
+    static PassOwnPtr<Canvas2DLayerBridge> create(PassRefPtr<GraphicsContext3D>, const IntSize&, OpacityMode, ThreadMode);
 
     virtual ~Canvas2DLayerBridge();
 
@@ -84,11 +81,15 @@ public:
 
     WebKit::WebLayer* layer();
     void contextAcquired();
+    SkCanvas* getCanvas() {return m_canvas;}
 
     unsigned backBufferTexture();
 
+    virtual bool isValid(); // virtual for faking
+
 protected:
-    Canvas2DLayerBridge(PassRefPtr<GraphicsContext3D>, SkDeferredCanvas*, OpacityMode, ThreadMode);
+    Canvas2DLayerBridge(PassRefPtr<GraphicsContext3D>, SkDeferredCanvas*);
+    void init(OpacityMode, ThreadMode);
 
     SkDeferredCanvas* m_canvas;
     OwnPtr<WebKit::WebExternalTextureLayer> m_layer;