Fill incomplete images in SkCodec parent class

src/codec/SkCodec_libgif.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.
  */
 
 #include "SkCodec.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
@@ skipping 53 matching lines @@
      */
     Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&,
             SkPMColor*, int32_t*) override;
 
     SkEncodedFormat onGetEncodedFormat() const override {
         return kGIF_SkEncodedFormat;
     }
 
     bool onRewind() override;
 
+    uint32_t onGetFillValue(const SkImageInfo& dstInfo) const override;
+
 private:
 
     /*
      * A gif can contain multiple image frames.  We will only decode the first
      * frame.  This function reads up to the first image frame, processing
      * transparency and/or animation information that comes before the image
      * data.
      *
      * @param gif        Pointer to the library type that manages the gif decode
      * @param transIndex This call will set the transparent index based on the
@@ skipping 81 matching lines @@
     const uint32_t                          fTransIndex;
     uint32_t                                fFillIndex;
     bool                                    fFrameIsSubset;
     SkAutoTDelete<SkSwizzler>               fSwizzler;
     SkAutoTUnref<SkColorTable>              fColorTable;
 
     friend class SkGifScanlineDecoder;
 
     typedef SkCodec INHERITED;
 };