[ObjC ARC] Converts ios/chrome/browser/ui/dialogs:unit_tests_internal to ARC.

ios/chrome/browser/ui/dialogs/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.
 
 source_set("dialogs") {
   deps = [
     "//base",
     "//ios/web",
   ]
 
@@ skipping 40 matching lines @@
     "//ios/chrome/browser/ui",
     "//ios/chrome/browser/ui/alert_coordinator",
     "//ios/web",
     "//ui/base",
     "//url",
   ]
   libs = [ "UIKit.framework" ]
 }
 
 source_set("unit_tests_internal") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   testonly = true
   sources = [
     "dialog_presenter_unittest.mm",
     "nsurl_protection_space_util_unittest.mm",
   ]
   deps = [
     ":dialogs_internal",
     "//base",
     "//components/strings",
     "//ios/chrome/app/strings",
@@ skipping 27 matching lines @@
     "//ios/web",
     "//ios/web:test_support",
     "//ui/base",
     "//url",
   ]
   libs = [
     "UIKit.framework",
     "XCTest.framework",
   ]
 }