Delete SkColorSpace::gammaNamed() from public API

src/image/SkSurface_Gpu.cpp

Index: src/image/SkSurface_Gpu.cpp
diff --git a/src/image/SkSurface_Gpu.cpp b/src/image/SkSurface_Gpu.cpp
index ebe103ac5a7bd3afcc7ede140bbe15e379ed9249..3007313118c9427fe2acc2c95838a389dea2f3a3 100644
--- a/src/image/SkSurface_Gpu.cpp
+++ b/src/image/SkSurface_Gpu.cpp
@@ -136,8 +136,7 @@ void SkSurface_Gpu::onPrepareForExternalIO() {
 bool SkSurface_Gpu::Valid(const SkImageInfo& info) {
     switch (info.colorType()) {
         case kRGBA_F16_SkColorType:
-            return info.colorSpace() &&
-                   SkColorSpace::kLinear_GammaNamed == info.colorSpace()->gammaNamed();
+            return info.colorSpace() && info.colorSpace()->gammaIsLinear();
         case kRGBA_8888_SkColorType:
         case kBGRA_8888_SkColorType:
             return !info.colorSpace() || info.colorSpace()->gammaCloseToSRGB();
@@ -149,7 +148,7 @@ bool SkSurface_Gpu::Valid(const SkImageInfo& info) {
 bool SkSurface_Gpu::Valid(GrContext* context, GrPixelConfig config, SkColorSpace* colorSpace) {
     switch (config) {
         case kRGBA_half_GrPixelConfig:
-            return colorSpace && SkColorSpace::kLinear_GammaNamed == colorSpace->gammaNamed();
+            return colorSpace && colorSpace->gammaIsLinear();
         case kSRGBA_8888_GrPixelConfig:
         case kSBGRA_8888_GrPixelConfig:
             return context->caps()->srgbSupport() && colorSpace && colorSpace->gammaCloseToSRGB();