Convert GN visibility variables to lists.

content/browser/devtools/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("//tools/grit/grit_rule.gni")
 
 # In GYP: devtools_resources target.
 group("resources") {
   deps = [
     ":devtools_resources",
@@ skipping 19 matching lines @@
     "SHARED_INTERMEDIATE_DIR=" + rebase_path(root_gen_dir, root_build_dir),
   ]
 
   deps = [
     # This is the action that generates out .grd input file.
     "//third_party/WebKit/public:blink_generate_devtools_grd",
   ]
 }
 
 action("gen_devtools_protocol_constants") {
-  visibility = ":devtools_protocol_constants"
+  visibility = [ ":devtools_protocol_constants" ]
 
   script = "//content/public/browser/devtools_protocol_constants_generator.py"
 
   blink_protocol = "//third_party/WebKit/Source/devtools/protocol.json"
   browser_protocol = "browser_protocol.json"
   inputs = [ blink_protocol, browser_protocol ]
 
   outputs = [
     "$target_gen_dir/devtools_protocol_constants.cc",
     "$target_gen_dir/devtools_protocol_constants.h",
   ]
 
   args = [ "content" ] + rebase_path(outputs, root_build_dir) + [
     rebase_path(blink_protocol, root_build_dir),
     rebase_path(browser_protocol, root_build_dir),
   ]
 }
 
 source_set("devtools_protocol_constants") {
-  visibility = ":resources"
+  visibility = [ ":resources" ]
   sources = get_target_outputs(":gen_devtools_protocol_constants")
 }