Refactor SkBitmapRegionDecoderInterface for Android

tools/SkBitmapRegionCanvas.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBitmapRegionDecoderInterface.h"
 #include "SkCodec.h"
 
 /*
  * This class implements SkBitmapRegionDecoder using an SkCodec and
  * an SkCanvas.  It uses the scanline decoder to subset the height.  It then
  * will subset the width and scale by drawing to an SkCanvas.
  */
 // FIXME (msarett): This implementation does not support WEBP, because WEBP
 // does not have a scanline decoder.
 class SkBitmapRegionCanvas : public SkBitmapRegionDecoderInterface {
 public:
 
     /*
      * Takes ownership of pointer to decoder
      */
     SkBitmapRegionCanvas(SkCodec* decoder);
 
-    /*
-     * Three differences from the Android version:
-     *     Returns a Skia bitmap instead of an Android bitmap.
-     *     Android version attempts to reuse a recycled bitmap.
-     *     Removed the options object and used parameters for color type and
-     *     sample size.
-     */
-    SkBitmap* decodeRegion(int start_x, int start_y, int width, int height,
-                           int sampleSize, SkColorType prefColorType) override;
+    bool decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* allocator,
+                      const SkIRect& desiredSubset, int sampleSize,
+                      SkColorType colorType, bool requireUnpremul) override;
 
     bool conversionSupported(SkColorType colorType) override;
 
 private:
 
     SkAutoTDelete<SkCodec> fDecoder;
 
     typedef SkBitmapRegionDecoderInterface INHERITED;
 
 };