[ObjC ARC] Converts ios/chrome/browser/ui/stack_view:perf_tests to ARC.

ios/chrome/browser/ui/stack_view/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/border_frame_bottom.png",
     "resources/border_frame_bottom@2x.png",
     "resources/border_frame_bottom@3x.png",
     "resources/border_frame_incognito_bottom.png",
@@ skipping 134 matching lines @@
     "//ios/chrome/browser/ui/tools_menu",
     "//ios/chrome/test/app:test_support",
     "//ios/chrome/test/earl_grey:test_support",
     "//ios/testing:ios_test_support",
     "//ios/testing/earl_grey:earl_grey_support",
   ]
   libs = [ "XCTest.framework" ]
 }
 
 source_set("perf_tests") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   testonly = true
   sources = [
     "stack_view_controller_perftest.mm",
   ]
   deps = [
     ":stack_view",
     "//base",
     "//base/test:test_support",
     "//ios/chrome/browser/snapshots",
     "//ios/chrome/browser/tabs",
     "//ios/chrome/browser/test:perf_test_support",
     "//ios/chrome/browser/ui",
     "//ios/chrome/browser/ui:ui_internal",
     "//ios/web",
     "//net",
   ]
   libs = [ "UIKit.framework" ]
 }