Convert GN visibility variables to lists.

components/search_engines/BUILD.gn

 # Copyright 2014 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("//tools/json_to_struct/json_to_struct.gni")
 
 static_library("search_engines") {
   sources = [
     "default_search_manager.cc",
@@ skipping 55 matching lines @@
       "default_search_policy_handler.cc",
       "default_search_policy_handler.h",
     ]
     deps += [
       "//components/policy",
     ]
   }
 }
 
 json_to_struct("prepopulated_engines") {
-  visibility = ":*"
+  visibility = [ ":*" ]
 
   source = "prepopulated_engines.json"
   schema_file = "prepopulated_engines_schema.json"
   namespace = "TemplateURLPrepopulateData"
 }