[ObjC ARC] Converts ios/chrome/browser/ui/settings:unit_tests to ARC.

ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm

Index: ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm
diff --git a/ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm b/ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm
index e60370113ff5d53e39017f43b629aade49acc6d8..1d07ba6928ef51a03d9ddafca280c8e32db9a49f 100644
--- a/ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm
+++ b/ios/chrome/browser/ui/settings/content_settings_collection_view_controller_unittest.mm
@@ -9,6 +9,10 @@
 #include "ios/chrome/grit/ios_strings.h"
 #include "ios/web/public/test/test_web_thread_bundle.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 class ContentSettingsCollectionViewControllerTest
@@ -20,7 +24,7 @@ class ContentSettingsCollectionViewControllerTest
     chrome_browser_state_ = test_cbs_builder.Build();
   }
 
-  CollectionViewController* NewController() override NS_RETURNS_RETAINED {
+  CollectionViewController* InstantiateController() override {
     return [[ContentSettingsCollectionViewController alloc]
         initWithBrowserState:chrome_browser_state_.get()];
   }