[ObjC ARC] Converts ios/chrome/browser/ui/reading_list:eg_tests to ARC.

ios/chrome/browser/ui/reading_list/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/distillation_fail.png",
     "resources/distillation_fail@2x.png",
     "resources/distillation_fail@3x.png",
     "resources/distillation_success.png",
@@ skipping 90 matching lines @@
     "//ios/chrome/browser/ui",
     "//ios/chrome/browser/ui/static_content",
     "//ios/web",
     "//ios/web:test_support",
     "//testing/gtest",
     "//third_party/ocmock",
   ]
 }
 
 source_set("eg_tests") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   testonly = true
   sources = [
     "reading_list_egtest.mm",
   ]
   deps = [
     ":reading_list",
     "//base",
     "//components/reading_list/ios",
     "//ios/chrome/app/strings",
     "//ios/chrome/browser/reading_list",
     "//ios/chrome/browser/ui/commands",
     "//ios/chrome/test/app:test_support",
     "//ios/chrome/test/earl_grey:test_support",
     "//ios/testing:ios_test_support",
     "//ios/third_party/earl_grey",
     "//ios/third_party/material_components_ios",
     "//ios/web:test_support",
   ]
   libs = [
     "UIKit.framework",
     "XCTest.framework",
   ]
 }