Store the "browser autorestarted, last session must be restored" information in a preference.

chrome/browser/browser_shutdown.cc

Index: chrome/browser/browser_shutdown.cc
diff --git a/chrome/browser/browser_shutdown.cc b/chrome/browser/browser_shutdown.cc
index 044b5051e3534765b792c58cc704d7807f90bb95..7f46b5e493a923d0f90f1f89e6c240a57303598d 100644
--- a/chrome/browser/browser_shutdown.cc
+++ b/chrome/browser/browser_shutdown.cc
@@ -218,10 +218,6 @@ void ShutdownPostThreadsStop(bool restart_last_session) {
       else
         new_cl->AppendSwitch(i->first);
     }
-    // Ensure restore last session is set.
-    if (!new_cl->HasSwitch(switches::kRestoreLastSession))
-      new_cl->AppendSwitch(switches::kRestoreLastSession);
-
     upgrade_util::RelaunchChromeBrowser(*new_cl.get());
 #else
     NOTIMPLEMENTED();