Delete SkColorSpace::gammaNamed() from public API

src/image/SkSurface_Raster.cpp

Index: src/image/SkSurface_Raster.cpp
diff --git a/src/image/SkSurface_Raster.cpp b/src/image/SkSurface_Raster.cpp
index 9309487c2b5f5f60f6a62c20056e9cf86444d19f..f2cb94a04f75f48501a362cf840e3d9fee741504 100644
--- a/src/image/SkSurface_Raster.cpp
+++ b/src/image/SkSurface_Raster.cpp
@@ -67,8 +67,7 @@ bool SkSurface_Raster::Valid(const SkImageInfo& info, size_t rowBytes) {
             shift = 2;
             break;
         case kRGBA_F16_SkColorType:
-            if (!info.colorSpace() ||
-                SkColorSpace::kLinear_GammaNamed != info.colorSpace()->gammaNamed()) {
+            if (!info.colorSpace() || !info.colorSpace()->gammaIsLinear()) {
                 return false;
             }
             shift = 3;