Introduce GrColorSpaceXform, for gamut conversion on textures

experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDither.h"
 #include "SkPerlinNoiseShader2.h"
 #include "SkColorFilter.h"
@@ skipping 665 matching lines @@
     }
 
     GrPerlinNoise2Effect(SkPerlinNoiseShader2::Type type,
                         int numOctaves, bool stitchTiles,
                         SkPerlinNoiseShader2::PaintingData* paintingData,
                         GrTexture* permutationsTexture, GrTexture* noiseTexture,
                         const SkMatrix& matrix)
       : fType(type)
       , fNumOctaves(numOctaves)
       , fStitchTiles(stitchTiles)
-      , fPermutationsAccess(permutationsTexture)
-      , fNoiseAccess(noiseTexture)
+      , fPermutationsAccess(permutationsTexture, nullptr)
+      , fNoiseAccess(noiseTexture, nullptr)
       , fPaintingData(paintingData) {
         this->initClassID<GrPerlinNoise2Effect>();
         this->addTextureAccess(&fPermutationsAccess);
         this->addTextureAccess(&fNoiseAccess);
         fCoordTransform.reset(kLocal_GrCoordSet, matrix);
         this->addCoordTransform(&fCoordTransform);
     }
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
 
@@ skipping 390 matching lines @@
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
         inout->setToUnknown(GrInvariantOutput::kWillNot_ReadInput);
     }
 
     GrImprovedPerlinNoiseEffect(int octaves, SkScalar z, 
                                 SkPerlinNoiseShader2::PaintingData* paintingData,
                                 GrTexture* permutationsTexture, GrTexture* gradientTexture,
                                 const SkMatrix& matrix)
       : fOctaves(octaves)
       , fZ(z)
-      , fPermutationsAccess(permutationsTexture)
-      , fGradientAccess(gradientTexture)
+      , fPermutationsAccess(permutationsTexture, nullptr)
+      , fGradientAccess(gradientTexture, nullptr)
       , fPaintingData(paintingData) {
         this->initClassID<GrImprovedPerlinNoiseEffect>();
         this->addTextureAccess(&fPermutationsAccess);
         this->addTextureAccess(&fGradientAccess);
         fCoordTransform.reset(kLocal_GrCoordSet, matrix);
         this->addCoordTransform(&fCoordTransform);
     }
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
 
@@ skipping 290 matching lines @@
     str->append(" seed: ");
     str->appendScalar(fSeed);
     str->append(" stitch tiles: ");
     str->append(fStitchTiles ? "true " : "false ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif