Add NewRGB() with float gamma to SkColorSpace public API

src/core/SkColorSpace_Base.h

Index: src/core/SkColorSpace_Base.h
diff --git a/src/core/SkColorSpace_Base.h b/src/core/SkColorSpace_Base.h
index 04f9b0b10848e168eae4f04f79552a7456c8b6f5..36cc47779a8d3a8f374809bb58b626cfbb7bb1c4 100644
--- a/src/core/SkColorSpace_Base.h
+++ b/src/core/SkColorSpace_Base.h
@@ -169,9 +169,6 @@ struct SkColorLookUpTable : public SkRefCnt {
 
 class SkColorSpace_Base : public SkColorSpace {
 public:
-
-    static sk_sp<SkColorSpace> NewRGB(const float gammas[3], const SkMatrix44& toXYZD50);
-
     SkGammaNamed gammaNamed() const { return fGammaNamed; }
     const SkGammas* gammas() const { return fGammas.get(); }