Fix SkSwizzler bug

src/codec/SkSwizzler.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 SkSwizzler_DEFINED
 #define SkSwizzler_DEFINED
 
@@ skipping 160 matching lines @@
                                    const uint8_t* SK_RESTRICT src,
                                    int dstWidth, int bpp, int deltaSrc, int offset,
                                    const SkPMColor ctable[]);
 
     const RowProc       fRowProc;
     const SkPMColor*    fColorTable;      // Unowned pointer
     const int           fSrcOffset;       // Offset of the src in pixels, allows for partial
                                           // scanline decodes.
     int                 fX0;              // Start coordinate for the src, may be different than
                                           // fSrcOffset if we are sampling.
-    const int           fSrcWidth;        // Width of the source - i.e. before any sampling.
+    const int           fSubsetWidth;     // Width of the subset of the source before any sampling.
     int                 fDstWidth;        // Width of dst, which may differ with sampling.
     int                 fSampleX;         // step between X samples
     const int           fBPP;             // if bitsPerPixel % 8 == 0
                                           //     fBPP is bytesPerPixel
                                           // else
                                           //     fBPP is bitsPerPixel
 
-    SkSwizzler(RowProc proc, const SkPMColor* ctable, int srcOffset, int srcWidth, int bpp);
+    SkSwizzler(RowProc proc, const SkPMColor* ctable, int srcOffset, int subsetWidth, int bpp);
 
     int onSetSampleX(int) override;
 
 };
 #endif // SkSwizzler_DEFINED