Enable sRGB on iOS, make sRGB decode support optional

tools/gpu/GrContextFactory.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrContextFactory_DEFINED
 #define GrContextFactory_DEFINED
 
@@ skipping 75 matching lines @@
     //! OpenGL or OpenGL ES context depending on the platform. To be removed.
     static const ContextType kNativeGL_ContextType;
 
     static const int kContextTypeCnt = kLastContextType + 1;
 
     /**
      * Options for GL context creation. For historical and testing reasons the options will default
      * to not using GL_NV_path_rendering extension  even when the driver supports it.
      */
     enum class ContextOptions {
-        kNone                = 0x0,
-        kEnableNVPR          = 0x1,
-        kUseInstanced        = 0x2,
-        kRequireSRGBSupport  = 0x4,
+        kNone                            = 0x0,
+        kEnableNVPR                      = 0x1,
+        kUseInstanced                    = 0x2,
+        kRequireSRGBSupport              = 0x4,
+        kRequireSRGBDecodeDisableSupport = 0x8,
     };
 
     static ContextType NativeContextTypeForBackend(GrBackend backend) {
         switch (backend) {
             case kOpenGL_GrBackend:
                 return kNativeGL_ContextType;
             case kVulkan_GrBackend:
                 return kVulkan_ContextType;
             default:
                 SkFAIL("Unknown backend");
@@ skipping 53 matching lines @@
     };
     SkTArray<Context, true>         fContexts;
     std::unique_ptr<GLTestContext>  fSentinelGLContext;
     const GrContextOptions          fGlobalOptions;
 };
 }  // namespace sk_gpu_test
 
 GR_MAKE_BITFIELD_CLASS_OPS(sk_gpu_test::GrContextFactory::ContextOptions);
 
 #endif