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

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

Index: ios/chrome/browser/ui/settings/voicesearch_collection_view_controller_unittest.mm
diff --git a/ios/chrome/browser/ui/settings/voicesearch_collection_view_controller_unittest.mm b/ios/chrome/browser/ui/settings/voicesearch_collection_view_controller_unittest.mm
index 7af6561ae6f8eccee40f0975860178c4be55079f..5d32f88ab37b1b0899802843139a169a2828bf9a 100644
--- a/ios/chrome/browser/ui/settings/voicesearch_collection_view_controller_unittest.mm
+++ b/ios/chrome/browser/ui/settings/voicesearch_collection_view_controller_unittest.mm
@@ -9,7 +9,6 @@
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/mac/foundation_util.h"
-#import "base/mac/scoped_nsobject.h"
 #include "base/message_loop/message_loop.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/prefs/pref_member.h"
@@ -25,6 +24,10 @@
 #include "testing/platform_test.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 class VoicesearchCollectionViewControllerTest
@@ -35,7 +38,7 @@ class VoicesearchCollectionViewControllerTest
     pref_service_ = CreateLocalState();
   }
 
-  CollectionViewController* NewController() override NS_RETURNS_RETAINED {
+  CollectionViewController* InstantiateController() override {
     return [[VoicesearchCollectionViewController alloc]
         initWithPrefs:pref_service_.get()];
   }