Introduce GrColorSpaceXform, for gamut conversion on textures

src/effects/SkDisplacementMapEffect.cpp

Index: src/effects/SkDisplacementMapEffect.cpp
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index 29ce3fef524c60e9e9c6c635218b64fc6ccfd93b..17336db7324f4b9d17a7df573c89893924687583 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -466,11 +466,11 @@ GrDisplacementMapEffect::GrDisplacementMapEffect(
                              const SkISize& colorDimensions)
     : fDisplacementTransform(kLocal_GrCoordSet, offsetMatrix, displacement,
                              GrTextureParams::kNone_FilterMode)
-    , fDisplacementAccess(displacement)
+    , fDisplacementAccess(displacement, nullptr)
     , fColorTransform(kLocal_GrCoordSet, color, GrTextureParams::kNone_FilterMode)
     , fDomain(GrTextureDomain::MakeTexelDomain(color, SkIRect::MakeSize(colorDimensions)),
               GrTextureDomain::kDecal_Mode)
-    , fColorAccess(color)
+    , fColorAccess(color, nullptr /* COLORXFORMTODO */)
     , fXChannelSelector(xChannelSelector)
     , fYChannelSelector(yChannelSelector)
     , fScale(scale) {