Add NewFromStream and getEncodedFormat to BitmapRegionDecoder

tools/SkBitmapRegionSampler.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 "SkImageDecoder.h"
@@ skipping 16 matching lines @@
                       SkColorType colorType, bool requireUnpremul) 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;
     }
 
+    SkEncodedFormat getEncodedFormat() override { return (SkEncodedFormat) fDecoder->getFormat(); }
+
 private:
 
     SkAutoTDelete<SkImageDecoder> fDecoder;
 
     typedef SkBitmapRegionDecoderInterface INHERITED;
 
 };