[ObjC ARC] Converts ios/chrome/browser/ui/print:eg_tests to ARC.

ios/chrome/browser/ui/print/print_controller_egtest.mm

Index: ios/chrome/browser/ui/print/print_controller_egtest.mm
diff --git a/ios/chrome/browser/ui/print/print_controller_egtest.mm b/ios/chrome/browser/ui/print/print_controller_egtest.mm
index af706fc2976066138829ed0c61f4b9dd170f2d52..c5f7987dfff5db4cdf3b6cb92d63a51af9d7229b 100644
--- a/ios/chrome/browser/ui/print/print_controller_egtest.mm
+++ b/ios/chrome/browser/ui/print/print_controller_egtest.mm
@@ -17,6 +17,10 @@
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // URL which leads to a PDF file.
 const char kPDFURL[] = "http://ios/testing/data/http_server_files/testpage.pdf";