Fix tabs duplication when restoring last closed window.

components/sessions/core/tab_restore_service_helper.h

 // Copyright 2012 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.
 
 #ifndef COMPONENTS_SESSIONS_CORE_TAB_RESTORE_SERVICE_HELPER_H_
 #define COMPONENTS_SESSIONS_CORE_TAB_RESTORE_SERVICE_HELPER_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 64 matching lines @@
   void CreateHistoricalTab(LiveTab* live_tab, int index);
   void BrowserClosing(LiveTabContext* context);
   void BrowserClosed(LiveTabContext* context);
   void ClearEntries();
   const Entries& entries() const;
   std::vector<LiveTab*> RestoreMostRecentEntry(LiveTabContext* context);
   std::unique_ptr<Tab> RemoveTabEntryById(SessionID::id_type id);
   std::vector<LiveTab*> RestoreEntryById(LiveTabContext* context,
                                          SessionID::id_type id,
                                          WindowOpenDisposition disposition);
+  bool IsRestoring() const;
 
   // Notifies observers the tabs have changed.
   void NotifyTabsChanged();
 
   // Notifies observers the service has loaded.
   void NotifyLoaded();
 
   // Adds |entry| to the list of entries. If |prune| is true |PruneAndNotify| is
   // invoked. If |to_front| is true the entry is added to the front, otherwise
   // the back. Normal closes go to the front, but tab/window closes from the
@@ skipping 80 matching lines @@
   std::set<LiveTabContext*> closing_contexts_;
 
   TimeFactory* const time_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TabRestoreServiceHelper);
 };
 
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_CORE_TAB_RESTORE_SERVICE_HELPER_H_