Introduce GrColorSpaceXform, for gamut conversion on textures

gm/texdata.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // This test only works with the GPU backend.
 
 #include "gm.h"
@@ skipping 80 matching lines @@
         if (i) {
             vm.setRotate(90 * SK_Scalar1,
                             S * SK_Scalar1,
                             S * SK_Scalar1);
         } else {
             vm.reset();
         }
         SkMatrix tm;
         tm = vm;
         tm.postIDiv(2*S, 2*S);
-        paint.addColorTextureProcessor(texture, tm);
+        paint.addColorTextureProcessor(texture, nullptr, tm);
 
         drawContext->drawRect(clip, paint, vm, SkRect::MakeWH(2*S, 2*S));
 
         // now update the lower right of the texture in first pass
         // or upper right in second pass
         offset = 0;
         for (int y = 0; y < S; ++y) {
             for (int x = 0; x < S; ++x) {
                 gTextureData[offset + y * stride + x] =
                     ((x + y) % 2) ? (i ? green : red) : blue;
             }
         }
         texture->writePixels(S, (i ? 0 : S), S, S,
                                 texture->config(), gTextureData.get(),
                                 4 * stride);
         drawContext->drawRect(clip, paint, vm, SkRect::MakeWH(2*S, 2*S));
     }
 }
 #endif