Enable sRGB on iOS, make sRGB decode support optional

include/gpu/GrContextOptions.h

Index: include/gpu/GrContextOptions.h
diff --git a/include/gpu/GrContextOptions.h b/include/gpu/GrContextOptions.h
index 6a1b51b5a67645ffdce9d186107e2dd9471b5018..65daf72eadd4d6284629fbe139835b84d9e071b4 100644
--- a/include/gpu/GrContextOptions.h
+++ b/include/gpu/GrContextOptions.h
@@ -77,6 +77,14 @@ struct GrContextOptions {
      * 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