[MD History] Fix toolbar dates in grouped mode.

chrome/browser/ui/webui/md_history_ui.cc

 // Copyright 2015 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 "chrome/browser/ui/webui/md_history_ui.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/values.h"
@@ skipping 61 matching lines @@
       "deleteWarning", IDS_HISTORY_DELETE_PRIOR_VISITS_WARNING_NO_INCOGNITO);
   source->AddLocalizedString("entrySummary", IDS_HISTORY_ENTRY_SUMMARY);
   source->AddLocalizedString("expandSessionButton",
                              IDS_HISTORY_OTHER_SESSIONS_EXPAND_SESSION);
   source->AddLocalizedString("foundSearchResults",
                              IDS_HISTORY_FOUND_SEARCH_RESULTS);
   source->AddLocalizedString("hasSyncedResults",
                              IDS_MD_HISTORY_HAS_SYNCED_RESULTS);
   source->AddLocalizedString("hasSyncedResultsDescription",
                              IDS_MD_HISTORY_HAS_SYNCED_RESULTS_DESCRIPTION);
-  source->AddLocalizedString("historyInterval", IDS_HISTORY_INTERVAL);
   source->AddLocalizedString("historyMenuButton",
                              IDS_MD_HISTORY_HISTORY_MENU_DESCRIPTION);
   source->AddLocalizedString("historyMenuItem",
                              IDS_MD_HISTORY_HISTORY_MENU_ITEM);
   source->AddLocalizedString("itemsSelected", IDS_MD_HISTORY_ITEMS_SELECTED);
   source->AddLocalizedString("loading", IDS_HISTORY_LOADING);
   source->AddLocalizedString("menuPromo", IDS_MD_HISTORY_MENU_PROMO);
   source->AddLocalizedString("moreActionsButton",
                              IDS_HISTORY_ACTION_MENU_DESCRIPTION);
   source->AddLocalizedString("moreFromSite", IDS_HISTORY_MORE_FROM_SITE);
@@ skipping 176 matching lines @@
 
   content::WebUIDataSource::Update(profile, chrome::kChromeUIHistoryHost,
                                    std::move(update));
 }
 
 void MdHistoryUI::HandleMenuPromoShown(const base::ListValue* args) {
   Profile::FromWebUI(web_ui())->GetPrefs()->SetBoolean(
       prefs::kMdHistoryMenuPromoShown, true);
   UpdateDataSource();
 }