Fix tabs duplication when restoring last closed window.

chrome/browser/sessions/session_service.h

Index: chrome/browser/sessions/session_service.h
diff --git a/chrome/browser/sessions/session_service.h b/chrome/browser/sessions/session_service.h
index 94aab17a721e89ffc0ed26de2723ee232b0ec377..762718bfea3a86dcf27e406c8c13571e9f944624 100644
--- a/chrome/browser/sessions/session_service.h
+++ b/chrome/browser/sessions/session_service.h
@@ -142,7 +142,8 @@ class SessionService : public sessions::BaseSessionServiceDelegate,
                  bool closed_by_user_gesture);
 
   // Notification a window has opened.
-  void WindowOpened(Browser* browser);
+  // Do not perform restoration if |dont_restore| is true.
+  void WindowOpened(Browser* browser, bool dont_restore);
 
   // Notification the window is about to close.
   void WindowClosing(const SessionID& window_id);
@@ -248,8 +249,9 @@ class SessionService : public sessions::BaseSessionServiceDelegate,
 
   // Implementation of RestoreIfNecessary. If |browser| is non-null and we need
   // to restore, the tabs are added to it, otherwise a new browser is created.
+  // Skip restoration if |dont_restore| is true.
   bool RestoreIfNecessary(const std::vector<GURL>& urls_to_open,
-                          Browser* browser);
+                          Browser* browser, bool dont_restore);
 
   void Observe(int type,
                const content::NotificationSource& source,