Remove png_read_end from SkPngScanlineDecoder

src/codec/SkCodec_libpng.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 "SkEncodedFormat.h"
@@ skipping 41 matching lines @@
     SkPngCodec(const SkImageInfo&, SkStream*, png_structp, png_infop, int);
 
 
     // Helper to set up swizzler and color table. Also calls png_read_update_info.
     Result initializeSwizzler(const SkImageInfo& requestedInfo, void* dst,
                               size_t rowBytes, const Options&, SkPMColor*, int* ctableCount);
 
     // Calls rewindIfNeeded and returns true if the decoder can continue.
     bool handleRewind();
     bool decodePalette(bool premultiply, int* ctableCount);
-    void finish();
     void destroyReadStruct();
 
     friend class SkPngScanlineDecoder;
     friend class SkPngInterlacedScanlineDecoder;
 
     typedef SkCodec INHERITED;
 };