Make imageSkia:::extractSubset multi-image aware.

ui/gfx/image/image_skia.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_IMAGE_IMAGE_SKIA_H_
 #define UI_GFX_IMAGE_IMAGE_SKIA_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 83 matching lines @@
 
   // Returns true if this is a null object.
   // TODO(pkotwicz): Merge this function into empty().
   bool isNull() const { return storage_ == NULL; }
 
   // Width and height of image in DIP coordinate system.
   int width() const;
   int height() const;
 
   // Wrapper function for SkBitmap::extractBitmap.
-  // Operates on bitmap at index 0 if available.
-  // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
-  // done.
+  // Operates on each stored bitmap.
   bool extractSubset(ImageSkia* dst, const SkIRect& subset) const;
 
   // Returns pointer to an SkBitmap contained by this object.
   // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
   // done.
   const SkBitmap* bitmap() const;
 
   // Returns a vector with the SkBitmaps contained in this object.
   const std::vector<SkBitmap> bitmaps() const;
 
@@ skipping 21 matching lines @@
   // A null bitmap to return as not to return a temporary.
   static SkBitmap* null_bitmap_;
 
   // A refptr so that ImageRepSkia can be copied cheaply.
   scoped_refptr<internal::ImageSkiaStorage> storage_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_SKIA_H_