Implementation of 2D canvas context lost/restored events

Source/platform/graphics/Canvas2DImageBufferSurface.h

Index: Source/platform/graphics/Canvas2DImageBufferSurface.h
diff --git a/Source/platform/graphics/Canvas2DImageBufferSurface.h b/Source/platform/graphics/Canvas2DImageBufferSurface.h
index 5773765be50306f53e7fdac4273fd3e5925defdb..b56f1ec89b9da8a50f978e39bcfb0591cb090b99 100644
--- a/Source/platform/graphics/Canvas2DImageBufferSurface.h
+++ b/Source/platform/graphics/Canvas2DImageBufferSurface.h
@@ -55,11 +55,13 @@ public:
     // ImageBufferSurface implementation
     virtual void willUse() OVERRIDE { m_layerBridge->willUse(); }
     virtual SkCanvas* canvas() const OVERRIDE { return m_layerBridge->canvas(); }
-    virtual bool isValid() const OVERRIDE { return m_layerBridge && (m_layerBridge->surfaceIsValid() || m_layerBridge->recoverSurface()); }
+    virtual bool isValid() const OVERRIDE { return m_layerBridge && m_layerBridge->checkSurfaceValid(); }
+    virtual bool restore() OVERRIDE { return m_layerBridge->restoreSurface(); }
     virtual blink::WebLayer* layer() const OVERRIDE { return m_layerBridge->layer(); }
     virtual Platform3DObject getBackingTexture() const OVERRIDE { return m_layerBridge->getBackingTexture(); }
     virtual bool isAccelerated() const OVERRIDE { return m_layerBridge->isAccelerated(); }
     virtual void setIsHidden(bool hidden) OVERRIDE { m_layerBridge->setIsHidden(hidden); }
+    virtual void setImageBuffer(ImageBuffer* imageBuffer) OVERRIDE { m_layerBridge->setImageBuffer(imageBuffer); }
 
 private:
     RefPtr<Canvas2DLayerBridge> m_layerBridge;