Combine native sampling with sampling

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 15 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,
             AndroidOptions& options) override;
 
 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
+     *                          effective sample size done by fCodec.
+     *  @return SkISize The size that fCodec should scale to.
+     */
+    SkISize accountForNativeScaling(int* sampleSize, int* nativeSampleSize = nullptr) const;
 
     /**
      *  This fulfills the same contract as onGetAndroidPixels().
      *
      *  We call this function from onGetAndroidPixels() if we have determined
      *  that fCodec does not support the requested scale, and we need to
      *  provide the scale by sampling.
      */
     SkCodec::Result sampledDecode(const SkImageInfo& info, void* pixels, size_t rowBytes,
             AndroidOptions& options);
 
     SkAutoTDelete<SkCodec> fCodec;
 
     typedef SkAndroidCodec INHERITED;
 };
 #endif // SkSampledCodec_DEFINED