Use demux API in SkWebpCodec

src/codec/SkWebpCodec.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 SkWebpCodec_DEFINED
 #define SkWebpCodec_DEFINED
 
 #include "SkCodec.h"
 #include "SkColorSpace.h"
 #include "SkEncodedFormat.h"
 #include "SkImageInfo.h"
 #include "SkTypes.h"
 
 class SkStream;
+extern "C" {
+    struct WebPDemuxer;
+    void WebPDemuxDelete(WebPDemuxer* dmux);
+}
 
 static const size_t WEBP_VP8_HEADER_SIZE = 30;
 
 class SkWebpCodec final : public SkCodec {
 public:
     // Assumes IsWebp was called and returned true.
     static SkCodec* NewFromStream(SkStream*);
     static bool IsWebp(const void*, size_t);
 protected:
     Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&, SkPMColor*, int*, int*)
             override;
     SkEncodedFormat onGetEncodedFormat() const override { return kWEBP_SkEncodedFormat; }
 
     SkISize onGetScaledDimensions(float desiredScale) const override;
 
     bool onDimensionsSupported(const SkISize&) override;
 
     bool onGetValidSubset(SkIRect* /* desiredSubset */) const override;
 private:
-    SkWebpCodec(int width, int height, const SkEncodedInfo&, sk_sp<SkColorSpace>, SkStream*);
+    SkWebpCodec(int width, int height, const SkEncodedInfo&, sk_sp<SkColorSpace>, SkStream*,
+                WebPDemuxer*, sk_sp<SkData>);
+
+    SkAutoTCallVProc<WebPDemuxer, WebPDemuxDelete> fDemux;
+
+    // fDemux has a pointer into this data.
+    // This should not be freed until the decode is completed.
+    sk_sp<SkData> fData;
 
     typedef SkCodec INHERITED;
 };
 #endif // SkWebpCodec_DEFINED