Bug 577843 - Scale videos at YCbCr conversion time - r=roc a=blocking2.0

gfx/layers/ImageLayers.h

@@ -114,6 +114,7 @@ class THEBES_API ImageContainer {
   THEBES_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageContainer)
 
 public:
+  ImageContainer() {}
   virtual ~ImageContainer() {}
 
   /**
@@ -179,6 +180,13 @@ public:
    */
   virtual PRBool SetLayerManager(LayerManager *aManager) = 0;
 
+  /**
+   * Sets a size that the image is expected to be rendered at.
+   * This is a hint for image backends to optimize scaling.
+   * Default implementation in this class is to ignore the hint.
+   */
+  virtual void SetScaleHint(const gfxIntSize& /* aScaleHint */) { }
+
 protected:
   LayerManager* mManager;