Initial ASTC decoder -- currently only supports 2D LDR decomrpession modes.

src/utils/SkTextureCompressor_ASTC.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTextureCompressor_ASTC_DEFINED
 #define SkTextureCompressor_ASTC_DEFINED
 
 #include <stdint.h>
 
 // Forward declare
 class SkBlitter;
 
 namespace SkTextureCompressor {
 
     bool CompressA8To12x12ASTC(uint8_t* dst, const uint8_t* src,
                                int width, int height, int rowBytes);
 
     SkBlitter* CreateASTCBlitter(int width, int height, void* outputBuffer);
+
+    void DecompressASTC(uint8_t* dst, int dstRowBytes, const uint8_t* src,
+                        int width, int height, int blockDimX, int blockDimY);
 }
 
 #endif  // SkTextureCompressor_ASTC_DEFINED