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

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

Index: ios/chrome/browser/ui/settings/passphrase_collection_view_controller_test.mm
diff --git a/ios/chrome/browser/ui/settings/passphrase_collection_view_controller_test.mm b/ios/chrome/browser/ui/settings/passphrase_collection_view_controller_test.mm
index d821c5642c6a73abac8606438272426200fb7e8b..88a477171396259b953a9ea04dd2a86d4b5bc5d7 100644
--- a/ios/chrome/browser/ui/settings/passphrase_collection_view_controller_test.mm
+++ b/ios/chrome/browser/ui/settings/passphrase_collection_view_controller_test.mm
@@ -29,6 +29,10 @@
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using testing::DefaultValue;
 using testing::NiceMock;
 using testing::Return;