[ObjC ARC] Converts ios/chrome/browser/ui/elements:elements_internal to ARC.

ios/chrome/browser/ui/elements/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("elements") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "selector_coordinator.h",
     "selector_coordinator.mm",
     "selector_picker_presentation_controller.h",
@@ skipping 20 matching lines @@
     ":elements",
     ":elements_internal",
     "//base",
     "//base/test:test_support",
     "//testing/gtest",
     "//third_party/ocmock",
   ]
 }
 
 source_set("elements_internal") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "activity_overlay_coordinator.h",
     "activity_overlay_coordinator.mm",
     "activity_overlay_view_controller.h",
     "activity_overlay_view_controller.mm",
   ]
   deps = [
     "//base",
     "//ios/chrome/browser",
     "//ios/chrome/browser/ui",
     "//ios/chrome/browser/ui/material_components",
     "//ios/third_party/material_components_ios",
   ]
   libs = [ "UIKit.framework" ]
 }