[ObjC ARC] Converts ios/chrome/browser/ui/ntp:ntp_controller to ARC.

ios/chrome/browser/ui/ntp/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/bookmarks_bar_bg.png",
     "resources/bookmarks_bar_bg@2x.png",
     "resources/bookmarks_bar_bg@2x~ipad.png",
     "resources/bookmarks_bar_bg_pressed@2x~ipad.png",
@@ skipping 120 matching lines @@
     "//ios/chrome/browser/ui/commands",
     "//ios/chrome/browser/ui/content_suggestions:content_suggestions_util",
     "//ios/chrome/browser/ui/toolbar",
     "//ios/chrome/browser/ui/toolbar:resource_macros",
     "//ios/chrome/common",
     "//ui/base",
   ]
 }
 
 source_set("ntp_controller") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "new_tab_page_controller.h",
     "new_tab_page_controller.mm",
   ]
   deps = [
     ":ntp",
     ":ntp_internal",
     "//base",
     "//components/prefs",
     "//components/search_engines",
@@ skipping 181 matching lines @@
     "new_tab_page_perftest.mm",
   ]
   deps = [
     "//base/test:test_support",
     "//ios/chrome/browser/sessions",
     "//ios/chrome/browser/tabs",
     "//ios/chrome/browser/test:perf_test_support",
     "//ios/chrome/browser/ui:ui_internal",
   ]
 }