Use SkImage snapshots for ImageBufferSurface texture access

Source/platform/graphics/ImageBufferSurface.h

Index: Source/platform/graphics/ImageBufferSurface.h
diff --git a/Source/platform/graphics/ImageBufferSurface.h b/Source/platform/graphics/ImageBufferSurface.h
index 50e9636d7d94abd432fd65419bbdd89f62a2898d..f050c2edc568a7df86eb8b9a84f191ff196fb17a 100644
--- a/Source/platform/graphics/ImageBufferSurface.h
+++ b/Source/platform/graphics/ImageBufferSurface.h
@@ -62,11 +62,11 @@ public:
     virtual void willAccessPixels() { }
     virtual void didDraw(const FloatRect& rect) { }
     virtual bool isValid() const = 0;
-    virtual bool restore() { return false; };
-    virtual WebLayer* layer() const { return 0; };
+    virtual bool restore() { return false; }
+    virtual WebLayer* layer() const { return 0; }
     virtual bool isAccelerated() const { return false; }
     virtual bool isRecording() const { return false; }
-    virtual Platform3DObject getBackingTexture() const { return 0; }
+    virtual PassRefPtr<SkImage> getBackingTextureImage() const { return nullptr; }
     virtual void didModifyBackingTexture() { }
     virtual bool cachedBitmapEnabled() const { return false; }
     virtual bool isExpensiveToPaint() { return false; }