Convert GN visibility variables to lists.

skia/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 
@@ skipping 681 matching lines @@
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
     ":skia_config",
     "//build/config/compiler:no_chromium_code"
   ]
 
   deps = [
     "//base",
   ]
 
-  visibility = ":skia"
+  visibility = [ ":skia" ]
 }