Revert of Enable sRGB on iOS, make sRGB decode support optional

include/gpu/GrContextOptions.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrContextOptions_DEFINED
 #define GrContextOptions_DEFINED
 
@@ skipping 64 matching lines @@
      * are commonly rendered at the same scale and fractional translation.
      */
     bool fAllowPathMaskCaching = false;
 
     /**
      * Force all path draws to go through through the sw-rasterize-to-texture code path (assuming
      * the path is not recognized as a simpler shape (e.g. a rrect). This is intended for testing
      * purposes.
      */
     bool fForceSWPathMasks = false;
-
-    /**
-     * If true, sRGB support will not be enabled unless sRGB decoding can be disabled (via an
-     * extension). If mixed use of "legacy" mode and sRGB/color-correct mode is not required, this
-     * can be set to false, which will significantly expand the number of devices that qualify for
-     * sRGB support.
-     */
-    bool fRequireDecodeDisableForSRGB = true;
 };
 
 #endif