Refactor SkBitmapRegionDecoderInterface for Android

tools/SkBitmapRegionSampler.h

Index: tools/SkBitmapRegionSampler.h
diff --git a/tools/SkBitmapRegionSampler.h b/tools/SkBitmapRegionSampler.h
index 8ed95e25249b1cd4092fd095ca601c8c4164a33d..ac70030dc60310bf19a30d5e3fb47ffb18ff950e 100644
--- a/tools/SkBitmapRegionSampler.h
+++ b/tools/SkBitmapRegionSampler.h
@@ -22,28 +22,20 @@ public:
      */
     SkBitmapRegionSampler(SkImageDecoder* decoder, int width, int height);
 
-    /*
-     * 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 prepareRegion(const SkIRect& desiredSubset, int sampleSize,
+            SkColorType colorType, bool requireUnpremul, SkImageInfo* outSize) override;
 
-    bool conversionSupported(SkColorType colorType) override {
-        // SkBitmapRegionSampler does not allow the client to check if the conversion
-        // is supported.  We will return true as a default.  If the conversion is in
-        // fact not supported, decodeRegion() will ignore the prefColorType and choose
-        // its own color type.  We catch this and fail non-fatally in our test code.
-        return true;
-    }
+    bool decodeRegion(SkBitmap& bitmap) override;
 
 private:
 
     SkAutoTDelete<SkImageDecoder> fDecoder;
 
+
+    // Fields set by prepareRegion()
+    SkIRect     fSubset;     // Subset of the original image to decode
+    SkColorType fColorType;  // Color type to decode to
+
     typedef SkBitmapRegionDecoderInterface INHERITED;
 
 };