Add reallyHasAlpha() to SkAndroidCodec

src/codec/SkWebpAdapterCodec.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 SkWebpAdapterCodec_DEFINED
 #define SkWebpAdapterCodec_DEFINED
 
 #include "SkAndroidCodec.h"
@@ skipping 14 matching lines @@
 
     SkEncodedFormat onGetEncodedFormat() const override { return kWEBP_SkEncodedFormat; };
 
     SkISize onGetSampledDimensions(int sampleSize) const override;
 
     bool onGetSupportedSubset(SkIRect* desiredSubset) const override;
 
     SkCodec::Result onGetAndroidPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
             const AndroidOptions& options) override;
 
+    bool onReallyHasAlpha() const override { return fCodec->reallyHasAlpha(); }
+
 private:
 
     SkAutoTDelete<SkWebpCodec> fCodec;
 
     typedef SkAndroidCodec INHERITED;
 };
 #endif // SkWebpAdapterCodec_DEFINED