[ObjC ARC] Converts ios/chrome/browser/autocomplete to ARC.

ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.mm

Index: ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.mm
diff --git a/ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.mm b/ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.mm
index f65ed788dabdf337c036513af53003f7500cae67..a79c236887d507aa16770eacea40abde15d33383 100644
--- a/ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.mm
+++ b/ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.mm
@@ -9,6 +9,10 @@
 #include "ios/chrome/browser/chrome_url_util.h"
 #include "url/url_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 AutocompleteSchemeClassifierImpl::AutocompleteSchemeClassifierImpl() {}
 
 AutocompleteSchemeClassifierImpl::~AutocompleteSchemeClassifierImpl() {}