Split SkBmpCodec into three separate classes

src/codec/SkMasks.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 SkMasks_DEFINED
+#define SkMasks_DEFINED
+
 #include "SkTypes.h"
 
 /*
  *
  * Contains useful mask routines for SkMaskSwizzler
  *
  */
 class SkMasks {
 public:
 
@@ skipping 55 matching lines @@
      *
      */
     SkMasks(const MaskInfo red, const MaskInfo green, const MaskInfo blue,
             const MaskInfo alpha);
 
     const MaskInfo fRed;
     const MaskInfo fGreen;
     const MaskInfo fBlue;
     const MaskInfo fAlpha;
 };
+
+#endif