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

components/translate/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 = [
     "ios_translate_driver.h",
@@ skipping 25 matching lines @@
 
 js_compile_checked("injected_js") {
   visibility = [ ":browser" ]
   sources = [
     "resources/language_detection.js",
     "resources/translate_ios.js",
   ]
 }
 
 source_set("unit_tests") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   testonly = true
   sources = [
     "js_translate_manager_unittest.mm",
     "language_detection_controller_unittest.mm",
     "string_clipping_util_unittest.cc",
     "translate_controller_unittest.mm",
   ]
 
   deps = [
     ":browser",
     "//base",
     "//components/prefs:test_support",
     "//components/resources",
     "//components/translate/core/common",
     "//ios/web:test_support",
     "//testing/gtest",
     "//third_party/ocmock",
     "//ui/base",
     "//url",
   ]
 }