Introduce GrColorSpaceXform, for gamut conversion on textures

tools/gpu/GrTest.cpp

Index: tools/gpu/GrTest.cpp
diff --git a/tools/gpu/GrTest.cpp b/tools/gpu/GrTest.cpp
index 83ab4ea56f7d2a755f51992b81beb1f01dd4e6b2..c96cb37e57dd4795dee1747f5bfd0ed716393599 100644
--- a/tools/gpu/GrTest.cpp
+++ b/tools/gpu/GrTest.cpp
@@ -149,7 +149,7 @@ void SkGpuDevice::drawTexture(GrTexture* tex, const SkRect& dst, const SkPaint&
     textureMat[SkMatrix::kMTransX] = -dst.fLeft/dst.width();
     textureMat[SkMatrix::kMTransY] = -dst.fTop/dst.height();
 
-    grPaint.addColorTextureProcessor(tex, textureMat);
+    grPaint.addColorTextureProcessor(tex, nullptr, textureMat);
 
     fDrawContext->drawRect(GrNoClip(), grPaint, mat, dst);
 }