SkColorSpace: remove named API, add gamut API

BUG=skia:

Change-Id: I01c5e1874c9a034febc64e25b3aaafb5050393a6
Reviewed-on: https://skia-review.googlesource.com/8021
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
diff --git a/src/codec/SkWebpCodec.cpp b/src/codec/SkWebpCodec.cpp
index dbc141e..bd69f65 100644
--- a/src/codec/SkWebpCodec.cpp
+++ b/src/codec/SkWebpCodec.cpp
@@ -70,7 +70,7 @@
         }
     }
     if (!colorSpace) {
-        colorSpace = SkColorSpace::MakeNamed(SkColorSpace::kSRGB_Named);
+        colorSpace = SkColorSpace::MakeSRGB();
     }
 
     // Since we do not yet support animation, we get the |width|, |height|, |color|, and |alpha|