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

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

Index: ios/chrome/browser/ui/settings/search_engine_settings_collection_view_controller_unittest.mm
diff --git a/ios/chrome/browser/ui/settings/search_engine_settings_collection_view_controller_unittest.mm b/ios/chrome/browser/ui/settings/search_engine_settings_collection_view_controller_unittest.mm
index c493b2e231e8987cce499c04b2908959bddce179..73da07cd84b570b9772091694846fef9faeee801 100644
--- a/ios/chrome/browser/ui/settings/search_engine_settings_collection_view_controller_unittest.mm
+++ b/ios/chrome/browser/ui/settings/search_engine_settings_collection_view_controller_unittest.mm
@@ -21,6 +21,10 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 class SearchEngineSettingsCollectionViewControllerTest
@@ -39,7 +43,7 @@ class SearchEngineSettingsCollectionViewControllerTest
     template_url_service_->Load();
   }
 
-  CollectionViewController* NewController() override NS_RETURNS_RETAINED {
+  CollectionViewController* InstantiateController() override {
     return [[SearchEngineSettingsCollectionViewController alloc]
         initWithBrowserState:chrome_browser_state_.get()];
   }