Generalize mask helper a bit for compression

src/gpu/GrSWMaskHelper.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrSWMaskHelper_DEFINED
 #define GrSWMaskHelper_DEFINED
 
@@ skipping 88 matching lines @@
     SkMatrix        fMatrix;
     SkBitmap        fBM;
     SkDraw          fDraw;
     SkRasterClip    fRasterClip;
 
     // Actually sends the texture data to the GPU. This is called from
     // toTexture with the data filled in depending on the texture config.
     void sendTextureData(GrTexture *texture, const GrTextureDesc& desc,
                          const void *data, int rowbytes);
 
+    // Compresses the bitmap stored in fBM and sends the compressed data
+    // to the GPU to be stored in 'texture' using sendTextureData.
+    void compressTextureData(GrTexture *texture, const GrTextureDesc& desc);
+
     typedef SkNoncopyable INHERITED;
 };
 
 #endif // GrSWMaskHelper_DEFINED