Refactored SkColorSpace and added in a Lab PCS GM

src/core/SkColorSpaceXform.h

Index: src/core/SkColorSpaceXform.h
diff --git a/src/core/SkColorSpaceXform.h b/src/core/SkColorSpaceXform.h
index bb99071fe03388057c63e30327ca95bdb6ba23b5..1618a201f45d1606a6220a6bd36ae26d8ab843a1 100644
--- a/src/core/SkColorSpaceXform.h
+++ b/src/core/SkColorSpaceXform.h
@@ -12,6 +12,8 @@
 #include "SkColorSpace_Base.h"
 #include "SkImageInfo.h"
 
+class SkColorSpace_XYZTRC;
+
 class SkColorSpaceXform : SkNoncopyable {
 public:
 
@@ -80,10 +82,8 @@ public:
     static constexpr int      kDstGammaTableSize = 1024;
 
 private:
-    SkColorSpaceXform_Base(SkColorSpace* srcSpace, const SkMatrix44& srcToDst,
-                           SkColorSpace* dstSpace);
-
-    sk_sp<SkColorLookUpTable> fColorLUT;
+    SkColorSpaceXform_Base(const SkColorSpace_XYZTRC* srcSpace, const SkMatrix44& srcToDst,
+                           const SkColorSpace_XYZTRC* dstSpace);
 
     // Contain pointers into storage or pointers into precomputed tables.
     const float*              fSrcGammaTables[3];
@@ -93,10 +93,10 @@ private:
     float                     fSrcToDst[16];
 
     friend class SkColorSpaceXform;
-    friend std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(SkColorSpace* space);
+    friend std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(const SkColorSpace_XYZTRC* space);
 };
 
 // For testing.  Bypasses opts for when src and dst color spaces are equal.
-std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(SkColorSpace* space);
+std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(const SkColorSpace_XYZTRC* space);
 
 #endif