[iOS] Mark test bundle_data targets as testonly.

ui/resources/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")
 import("//tools/grit/repack.gni")
 
 # GYP version: ui/resources/ui_resources.gyp:ui_resources
 group("resources") {
   public_deps = [
@@ skipping 58 matching lines @@
     public_deps = [
       ":repack_ui_test_mac_locale_pack",
       ":repack_ui_test_pak",
     ]
   }
 
   # This needs to be a separate target from ui_test_pak as ui_base_unittests
   # wants the generate .pak file in the bundle to be named en.lpro/locale.pak
   # while components_unittests wants it to be named ui_test.pak.
   bundle_data("ui_test_pak_bundle_data") {
+    testonly = true
     public_deps = [
       ":ui_test_pak",
     ]
     sources = [
       "$root_out_dir/ui_test.pak",
     ]
     outputs = [
       "{{bundle_resources_dir}}/en.lproj/locale.pak",
     ]
   }
@@ skipping 91 matching lines @@
     "$root_gen_dir/ui/strings/app_locale_settings_en-US.pak",
     "$root_gen_dir/ui/strings/ui_strings_en-US.pak",
   ]
 
   output = "$root_out_dir/ui/en.lproj/locale.pak"
 
   deps = [
     "//ui/strings",
   ]
 }