Implement onSkipScanlines() for bmp and wbmp

src/codec/SkBmpStandardCodec.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 "SkBmpCodec.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
@@ skipping 72 matching lines @@
      *               Either way, this stream is unowned.
      */
     void decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes);
 
     SkAutoTUnref<SkColorTable>          fColorTable;     // owned
     // fNumColors is the number specified in the header, or 0 if not present in the header.
     const uint32_t                      fNumColors;
     const uint32_t                      fBytesPerColor;
     const uint32_t                      fOffset;
     SkAutoTDelete<SkSwizzler>           fSwizzler;
-    const size_t                        fSrcRowBytes;
     SkAutoTDeleteArray<uint8_t>         fSrcBuffer;
     const bool                          fIsOpaque;
     const bool                          fInIco;
     const size_t                        fAndMaskRowBytes; // only used for fInIco decodes
 
     typedef SkBmpCodec INHERITED;
 };