Refactored SkColorSpace and added in a Lab PCS GM

src/gpu/GrColorSpaceXform.cpp

Index: src/gpu/GrColorSpaceXform.cpp
diff --git a/src/gpu/GrColorSpaceXform.cpp b/src/gpu/GrColorSpaceXform.cpp
index d2270fafdd4a2458b4f8a1721be0a4f41f5adf26..d784a490b0f754b773ea144b33c6f3ed4d6778de 100644
--- a/src/gpu/GrColorSpaceXform.cpp
+++ b/src/gpu/GrColorSpaceXform.cpp
@@ -50,7 +50,11 @@ sk_sp<GrColorSpaceXform> GrColorSpaceXform::Make(SkColorSpace* src, SkColorSpace
     }
 
     SkMatrix44 srcToDst(SkMatrix44::kUninitialized_Constructor);
-    srcToDst.setConcat(as_CSB(dst)->fromXYZD50(), as_CSB(src)->toXYZD50());
+    const SkMatrix44* toXYZD50   = as_CSB(src)->requestToXYZD50();
+    SkASSERT(toXYZD50);
+    const SkMatrix44* fromXYZD50 = as_CSB(dst)->requestFromXYZD50();
+    SkASSERT(fromXYZD50);
+    srcToDst.setConcat(*fromXYZD50, *toXYZD50);
 
     if (matrix_is_almost_identity(srcToDst)) {
         return nullptr;