Add NewFromStream and getEncodedFormat to BitmapRegionDecoder

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"
@@ skipping 12 matching lines @@
      * Takes ownership of pointer to decoder
      */
     SkBitmapRegionCanvas(SkCodec* decoder);
 
     bool decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* allocator,
                       const SkIRect& desiredSubset, int sampleSize,
                       SkColorType colorType, bool requireUnpremul) override;
 
     bool conversionSupported(SkColorType colorType) override;
 
+    SkEncodedFormat getEncodedFormat() override { return fDecoder->getEncodedFormat(); }
+
 private:
 
     SkAutoTDelete<SkCodec> fDecoder;
 
     typedef SkBitmapRegionDecoderInterface INHERITED;
 
 };