New helper for creating a color space from another, with linear gamma

src/core/SkColorSpace.cpp

Index: src/core/SkColorSpace.cpp
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index 3a5d9c196a6e522637cd480fe16b6468df7beea2..35cfa5741c7db9d286d58008abd6a14042b1e7d9 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -155,6 +155,10 @@ sk_sp<SkColorSpace> SkColorSpace::NewNamed(Named named) {
     return nullptr;
 }
 
+sk_sp<SkColorSpace> SkColorSpace::makeLinearGamma() {
+    return SkColorSpace_Base::NewRGB(kLinear_GammaNamed, fToXYZD50);

[msarett, 2016/08/23 18:01:12]

Eventually we'll want to add once-ptrs for the common cases of this...

+}
+
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 enum Version {