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 6aa46d609f5877bb5e624ff66c4b45bf395a26c3..fe3cdd24b5791c3a44075a0808f3ff6619fdb612 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_XYZ.h"
 #include "SkColorSpaceXform.h"
 #include "SkCommandLineFlags.h"
 
@@ -170,7 +170,8 @@ void ColorCodecBench::onDelayedSetup() {
 
     if (FLAGS_half) {
         fDstInfo = fDstInfo.makeColorType(kRGBA_F16_SkColorType);
-        fDstSpace = as_CSB(fDstSpace)->makeLinearGamma();
+        SkASSERT(SkColorSpace_Base::Type::kXYZ == as_CSB(fDstSpace)->type());
+        fDstSpace = static_cast<SkColorSpace_XYZ*>(fDstSpace.get())->makeLinearGamma();
     }
 
     if (FLAGS_nonstd) {