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/dm/DM.cpp b/dm/DM.cpp
index ca8647f..81506a7 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -860,8 +860,8 @@
 #define SINK(t, sink, ...) if (config->getBackend().equals(t)) { return new sink(__VA_ARGS__); }
 
     if (FLAGS_cpu) {
-        auto srgbColorSpace = SkColorSpace::MakeNamed(SkColorSpace::kSRGB_Named);
-        auto srgbLinearColorSpace = SkColorSpace::MakeNamed(SkColorSpace::kSRGBLinear_Named);
+        auto srgbColorSpace = SkColorSpace::MakeSRGB();
+        auto srgbLinearColorSpace = SkColorSpace::MakeSRGBLinear();
 
         SINK("565",  RasterSink, kRGB_565_SkColorType);
         SINK("8888", RasterSink, kN32_SkColorType);