Added kSRGBLinear_Named color space, along with tests

tests/SurfaceTest.cpp

Index: tests/SurfaceTest.cpp
diff --git a/tests/SurfaceTest.cpp b/tests/SurfaceTest.cpp
index 775b8c6c0567c527aa6f76de15fbe7bfb3f40b78..6706fef7e4e1051d8b2f7ec5fe83496385f6bdec 100644
--- a/tests/SurfaceTest.cpp
+++ b/tests/SurfaceTest.cpp
@@ -924,7 +924,7 @@ static void test_surface_creation_and_snapshot_with_color_space(
     SkMatrix44 srgbMatrix = srgbColorSpace->toXYZD50();
     const float oddGamma[] = { 2.4f, 2.4f, 2.4f };
     auto oddColorSpace = SkColorSpace_Base::NewRGB(oddGamma, srgbMatrix);
-    auto linearColorSpace = srgbColorSpace->makeLinearGamma();
+    auto linearColorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGBLinear_Named);
 
     const struct {
         SkColorType         fColorType;