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

ios/chrome/browser/ui/history/history_util.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/chrome/browser/ui/history/history_util.h"
 
 #include <map>
 
 #include "base/i18n/time_formatting.h"
 #include "base/time/time.h"
 #include "components/strings/grit/components_strings.h"
 #include "ios/chrome/browser/ui/history/history_entry.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/time_format.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace history {
 
 base::string16 GetRelativeDateLocalized(const base::Time& visit_time) {
   base::Time midnight = base::Time::Now().LocalMidnight();
   base::string16 date_str = ui::TimeFormat::RelativeDate(visit_time, &midnight);
   if (date_str.empty()) {
     date_str = base::TimeFormatFriendlyDate(visit_time);
   } else {
     date_str = l10n_util::GetStringFUTF16(
         IDS_HISTORY_DATE_WITH_RELATIVE_TIME, date_str,
@@ skipping 36 matching lines @@
                                             entry.all_timestamps.end());
 
       if (combined_entry->entry_type != entry.entry_type) {
         combined_entry->entry_type = history::HistoryEntry::COMBINED_ENTRY;
       }
     }
   }
   entries->swap(new_entries);
 }
 }  // namespace history