SkColorSpace: remove named API, add gamut API

Reland from: https://skia-review.googlesource.com/c/8021/

BUG=skia:

Change-Id: I18985f130587b15fccbc86b76b2bb5c49ba5ba8a
Reviewed-on: https://skia-review.googlesource.com/8136
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
diff --git a/tests/SRGBMipMapTest.cpp b/tests/SRGBMipMapTest.cpp
index 22d6890..dbdcaec 100644
--- a/tests/SRGBMipMapTest.cpp
+++ b/tests/SRGBMipMapTest.cpp
@@ -121,7 +121,7 @@
     sk_sp<GrTexture> texture(texProvider->createTexture(desc, SkBudgeted::kNo, texData, 0));
 
     // Create two render target contexts (L32 and S32)
-    sk_sp<SkColorSpace> srgbColorSpace = SkColorSpace::MakeNamed(SkColorSpace::kSRGB_Named);
+    sk_sp<SkColorSpace> srgbColorSpace = SkColorSpace::MakeSRGB();
     sk_sp<GrRenderTargetContext> l32RenderTargetContext = context->makeRenderTargetContext(
         SkBackingFit::kExact, rtS, rtS, kRGBA_8888_GrPixelConfig, nullptr);
     sk_sp<GrRenderTargetContext> s32RenderTargetContext = context->makeRenderTargetContext(