Cache the inverse matrix on SkColorSpace. Rename xyz() to toXYZ().

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2323003002

Review-Url: https://codereview.chromium.org/2323003002
diff --git a/tests/TestConfigParsing.cpp b/tests/TestConfigParsing.cpp
index a68a52d..1804423 100644
--- a/tests/TestConfigParsing.cpp
+++ b/tests/TestConfigParsing.cpp
@@ -125,8 +125,8 @@
     REPORTER_ASSERT(reporter, configs[25]->asConfigGpu()->getColorType() == kRGBA_F16_SkColorType);
     REPORTER_ASSERT(reporter, configs[25]->asConfigGpu()->getColorSpace());
     REPORTER_ASSERT(reporter, configs[25]->asConfigGpu()->getColorSpace()->gammaIsLinear());
-    REPORTER_ASSERT(reporter, configs[25]->asConfigGpu()->getColorSpace()->xyz() ==
-                              srgbColorSpace->xyz());
+    REPORTER_ASSERT(reporter, configs[25]->asConfigGpu()->getColorSpace()->toXYZD50() ==
+                              srgbColorSpace->toXYZD50());
     REPORTER_ASSERT(reporter, configs[26]->asConfigGpu()->getColorType() == kN32_SkColorType);
     REPORTER_ASSERT(reporter, configs[26]->asConfigGpu()->getColorSpace() == srgbColorSpace.get());
     REPORTER_ASSERT(reporter, configs[33]->asConfigGpu()->getContextType() ==