[ObjC ARC] Converts ios/chrome/browser/browsing_data:browsing_data.

ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.mm

Index: ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.mm
diff --git a/ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.mm b/ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.mm
index 574684ad3bcc731526b14f7cf655616860bea07f..4f8a1cd6b4361c499c30129607f1085efb3c66fb 100644
--- a/ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.mm
+++ b/ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.mm
@@ -45,6 +45,10 @@
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_context_getter.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using base::UserMetricsAction;
 using web::WebThread;