Make drawImage a virtual on SkDevice

src/core/SkPaintPriv.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPaintPriv_DEFINED
 #define SkPaintPriv_DEFINED
 
+#include "SkTypes.h"
+
 class SkBitmap;
+class SkImage;
 class SkPaint;
 
-#include "SkTypes.h"
-
 enum SkPaintBitmapOpacity {
     // No content replaces the paint's color
     kNoBitmap_SkPaintBitmapOpacity = 0,
     // The color replacement is known to be opaque
     kOpaque_SkPaintBitmapOpacity = 1,
     // We have no information about the color or it is transparent
     kUnknown_SkPaintBitmapOpacity = 2
 };
 
 /** Returns true if draw calls that use the paint will completely occlude
     canvas contents that are covered by the draw.
     @param paint The paint to be analyzed, NULL is equivalent to
         the default paint.
     @param contentType The type of the content that will be drawn,
         kNoBitmap_SkPaintBitmapOpacity if there is no content in adition to the paint.
     @return true if paint is opaque
 */
 bool isPaintOpaque(const SkPaint* paint, SkPaintBitmapOpacity contentType);
 
 /** Returns true if draw calls that use the paint will completely occlude
     canvas contents that are covered by the draw.
     @param paint The paint to be analyzed, NULL is equivalent to
         the default paint.
     @param bmpReplacesShader a bitmap to be used in place of the paint's
         shader.
     @return true if paint is opaque
 */
-bool isPaintOpaque(const SkPaint* paint,
-                   const SkBitmap* bmpReplacesShader = NULL);
+bool isPaintOpaque(const SkPaint* paint, const SkBitmap* bmpReplacesShader = NULL);
+bool isPaintOpaque(const SkPaint* paint, const SkImage* image);
+
 #endif