Add reallyHasAlpha() to SkAndroidCodec

src/codec/SkSampledCodec.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.
  */
 #ifndef SkSampledCodec_DEFINED
 #define SkSampledCodec_DEFINED
 
 #include "SkAndroidCodec.h"
@@ skipping 14 matching lines @@
 
     SkEncodedFormat onGetEncodedFormat() const override { return fCodec->getEncodedFormat(); };
 
     SkISize onGetSampledDimensions(int sampleSize) const override;
 
     bool onGetSupportedSubset(SkIRect* desiredSubset) const override { return true; }
 
     SkCodec::Result onGetAndroidPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
             const AndroidOptions& options) override;
 
+    bool onReallyHasAlpha() const override { return fCodec->reallyHasAlpha(); }
+
 private:
     /**
      *  Find the best way to account for native scaling.
      *
      *  Return a size that fCodec can scale to, and adjust sampleSize to finish scaling.
      *
      *  @param sampleSize As an input, the requested sample size.
      *                    As an output, sampling needed after letting fCodec
      *                    scale to the returned dimensions.
      *  @param nativeSampleSize Optional output parameter. Will be set to the
@@ skipping 10 matching lines @@
      *  provide the scale by sampling.
      */
     SkCodec::Result sampledDecode(const SkImageInfo& info, void* pixels, size_t rowBytes,
             const AndroidOptions& options);
 
     SkAutoTDelete<SkCodec> fCodec;
 
     typedef SkAndroidCodec INHERITED;
 };
 #endif // SkSampledCodec_DEFINED