Create an SkAndroidCodec API separate from SkCodec

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"
+#include "SkWebpCodec.h"
+
+/**
+ *  This class implements the functionality of SkAndroidCodec.  It uses an
+ *  SkWebpCodec.
+ */
+class SkWebpAdapterCodec : public SkAndroidCodec {
+public:
+
+    explicit SkWebpAdapterCodec(SkWebpCodec*);
+
+    virtual ~SkWebpAdapterCodec() {}
+
+protected:
+
+    SkEncodedFormat onGetEncodedFormat() const override { return kWEBP_SkEncodedFormat; };
+
+    SkISize onGetSampledDimensions(int sampleSize) const override;
+
+    bool onGetSubset(SkIRect* desiredSubset) const override;
+
+    SkISize onGetSampledSubsetDimensions(int sampleSize, const SkIRect& subset) const override;
+
+    SkCodec::Result onGetAndroidPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
+            AndroidOptions& options) override;
+
+private:
+
+    SkAutoTDelete<SkWebpCodec> fCodec;
+
+    typedef SkAndroidCodec INHERITED;
+};
+#endif // SkWebpAdapterCodec_DEFINED