Convert GN visibility to lists.

Source/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.
 
 blink_devtools_output_dir = "$root_gen_dir/blink/devtools/"
 
 gypi_values = exec_script(
     "//build/gypi_to_gn.py",
     [ rebase_path("devtools.gypi") ],
     "scope",
@@ skipping 15 matching lines @@
   gypi_values.devtools_host_js_files +
   gypi_values.devtools_screencast_js_files +
   gypi_values.devtools_toolbox_js_files
 
 devtools_extensions_js_files = gypi_values.devtools_extensions_js_files -
   [ "<@(devtools_extension_api_files)" ] +
   gypi_values.devtools_extension_api_files
 
 #-------------------------------------------------------------------------------
 
-visibility = "//third_party/WebKit/*"
+visibility = [ "//third_party/WebKit/*" ]
 
 # Probably need to parameterize this. If we set it to true, there will be some
 # further work in the scripts below.
 debug_devtools = false
 
 group("devtools_frontend_resources") {
   deps = [
     ":build_audits_module",
     ":build_console_module",
     ":build_core_module",
@@ skipping 290 matching lines @@
   script = "scripts/concatenate_css_files.py"
 
   input_stylesheet = "front_end/inspector.css"
   inputs = [ input_stylesheet ] + devtools_core_base_files
 
   outputs = [ "$root_out_dir/resources/inspector/inspector.css" ]
 
   args = [ rebase_path(input_stylesheet, root_build_dir) ] +
     rebase_path(outputs, root_build_dir)
 }