[ObjC ARC] Converts components/autofill/ios/browser:browser to ARC.

components/autofill/ios/browser/BUILD.gn

 # Copyright 2015 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("//ios/web/js_compile.gni")
 
 source_set("browser") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "autofill_client_ios_bridge.h",
     "autofill_driver_ios.h",
     "autofill_driver_ios.mm",
     "autofill_driver_ios_bridge.h",
     "credit_card_util.h",
     "credit_card_util.mm",
     "form_suggestion.h",
     "form_suggestion.mm",
     "js_autofill_manager.h",
@@ skipping 14 matching lines @@
   ]
 }
 
 js_compile_checked("injected_js") {
   visibility = [ ":browser" ]
   sources = [
     "resources/autofill_controller.js",
     "resources/suggestion_controller.js",
   ]
 }