[ObjC ARC] Converts ios/chrome/browser/crash_report to ARC

ios/chrome/browser/crash_report/crash_report_user_application_state.mm

Index: ios/chrome/browser/crash_report/crash_report_user_application_state.mm
diff --git a/ios/chrome/browser/crash_report/crash_report_user_application_state.mm b/ios/chrome/browser/crash_report/crash_report_user_application_state.mm
index 70751eb939d4c047750e8cd3b42969c7d3722a58..e5a06895331fa7840f3ad39a2aee1f64138f81f8 100644
--- a/ios/chrome/browser/crash_report/crash_report_user_application_state.mm
+++ b/ios/chrome/browser/crash_report/crash_report_user_application_state.mm
@@ -4,6 +4,10 @@
 
 #import "ios/chrome/browser/crash_report/crash_report_user_application_state.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 NSString* const kBrowserState = @"user_application_state";
 }