Move all knowledge of X sampling into SkScaledCodec

src/codec/SkBmpCodec.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 SkBmpCodec_DEFINED
 #define SkBmpCodec_DEFINED
 
 #include "SkCodec.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
-#include "SkMaskSwizzler.h"
 #include "SkStream.h"
 #include "SkSwizzler.h"
 #include "SkTypes.h"
 
 /*
  * This class enables code sharing between its bmp codec subclasses.  The
  * subclasses actually do the work.
  */
 class SkBmpCodec : public SkCodec {
 public:
@@ skipping 130 matching lines @@
 
     // TODO(msarett): Override default skipping with something more clever.
 
     const uint16_t          fBitsPerPixel;
     const SkScanlineOrder   fRowOrder;
 
     typedef SkCodec INHERITED;
 };
 
 #endif