Introduce GrColorSpaceXform, for gamut conversion on textures

experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp

Index: experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
diff --git a/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp b/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
index b0c60f71610e5e48b2dd9a07ad892bd475e5533d..49ca9f36995b8759688b319e51a61d0086caf914 100644
--- a/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
+++ b/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
@@ -683,8 +683,8 @@ private:
       : fType(type)
       , fNumOctaves(numOctaves)
       , fStitchTiles(stitchTiles)
-      , fPermutationsAccess(permutationsTexture)
-      , fNoiseAccess(noiseTexture)
+      , fPermutationsAccess(permutationsTexture, nullptr)
+      , fNoiseAccess(noiseTexture, nullptr)
       , fPaintingData(paintingData) {
         this->initClassID<GrPerlinNoise2Effect>();
         this->addTextureAccess(&fPermutationsAccess);
@@ -1095,8 +1095,8 @@ private:
                                 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);