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/SpecialImageTest.cpp b/tests/SpecialImageTest.cpp
index 551efff..94683a0 100644
--- a/tests/SpecialImageTest.cpp
+++ b/tests/SpecialImageTest.cpp
@@ -184,7 +184,7 @@
 }
 
 DEF_TEST(SpecialImage_Image_ColorSpaceAware, reporter) {
-    sk_sp<SkColorSpace> srgbColorSpace = SkColorSpace::MakeNamed(SkColorSpace::kSRGB_Named);
+    sk_sp<SkColorSpace> srgbColorSpace = SkColorSpace::MakeSRGB();
     test_specialimage_image(reporter, srgbColorSpace.get());
 }