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 45 matching lines @@
      * Ownership is unchanged when we returned a gifOut.
      *
      */
     static bool ReadHeader(SkStream* stream, SkCodec** codecOut,
             GifFileType** gifOut);
 
     /*
      * Performs the full gif decode
      */
     Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&,
-            SkPMColor*, int32_t*) override;
+            SkPMColor*, int*, int*) 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 38 matching lines @@
      *
      * @param dstInfo  Output image information.  Dimensions may have been
      *                 adjusted if the image frame size does not match the size
      *                 indicated in the header.
      * @param zeroInit Indicates if destination memory is zero initialized.
      */
     SkCodec::Result initializeSwizzler(const SkImageInfo& dstInfo,
             ZeroInitialized zeroInit);
 
     /*
-     * @return kSuccess if the read is successful and kIncompleteInput if the
-     *         read fails.
+     * @return true if the read is successful and false if the read fails.
      */
-    SkCodec::Result readRow();
+    bool readRow();
 
     /*
      * This function cleans up the gif object after the decode completes
      * It is used in a SkAutoTCallIProc template
      */
     static void CloseGif(GifFileType* gif);
 
     /*
      * Frees any extension data used in the decode
      * Used in a SkAutoTCallVProc
@@ skipping 19 matching lines @@
     const uint32_t                          fTransIndex;
     uint32_t                                fFillIndex;
     bool                                    fFrameIsSubset;
     SkAutoTDelete<SkSwizzler>               fSwizzler;
     SkAutoTUnref<SkColorTable>              fColorTable;
 
     friend class SkGifScanlineDecoder;
 
     typedef SkCodec INHERITED;
 };