Refactored SkColorSpace and added in a Lab PCS GM

bench/ColorCodecBench.cpp

Index: bench/ColorCodecBench.cpp
diff --git a/bench/ColorCodecBench.cpp b/bench/ColorCodecBench.cpp
index 9ae5601d49ef512d8792ce1b25819e0505156c2b..a48576e5033efd06b8556622c2259702eed8cbbb 100644
--- a/bench/ColorCodecBench.cpp
+++ b/bench/ColorCodecBench.cpp
@@ -9,7 +9,7 @@
 #include "Resources.h"
 #include "SkCodec.h"
 #include "SkCodecPriv.h"
-#include "SkColorSpace_Base.h"
+#include "SkColorSpace_XYZTRC.h"
 #include "SkColorSpaceXform.h"
 #include "SkCommandLineFlags.h"
 
@@ -169,7 +169,8 @@ void ColorCodecBench::onDelayedSetup() {
 
     if (FLAGS_half) {
         fDstInfo = fDstInfo.makeColorType(kRGBA_F16_SkColorType);
-        fDstSpace = as_CSB(fDstSpace)->makeLinearGamma();
+        SkASSERT(as_CSB(fDstSpace)->toXYZD50());
+        fDstSpace = static_cast<SkColorSpace_XYZTRC*>(fDstSpace.get())->makeLinearGamma();
     }
 
     fDstInfo = fDstInfo.makeColorSpace(fDstSpace);