[ObjC ARC] Converts ios/chrome/browser/ui/settings:test_support to ARC.

ios/chrome/browser/ui/settings/BUILD.gn

 # Copyright 2016 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.
 
 bundle_data("resources") {
   sources = [
     "resources/app_icon_placeholder.png",
     "resources/app_icon_placeholder@2x.png",
     "resources/app_icon_placeholder@3x.png",
     "resources/encryption_error.png",
@@ skipping 286 matching lines @@
   ]
   libs = [
     "CoreLocation.framework",
     "LocalAuthentication.framework",
     "StoreKit.framework",
     "UIKit.framework",
   ]
 }
 
 source_set("test_support") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   testonly = true
   sources = [
     "passphrase_collection_view_controller_test.h",
     "passphrase_collection_view_controller_test.mm",
     "personal_data_manager_data_changed_observer.cc",
     "personal_data_manager_data_changed_observer.h",
   ]
   deps = [
     ":settings",
     "//base",
@@ skipping 161 matching lines @@
     "//ios/web:test_support",
     "//net",
     "//ui/base",
     "//url",
   ]
   libs = [
     "UIKit.framework",
     "XCTest.framework",
   ]
 }