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

chrome/browser/browser_shutdown.cc

 // Copyright (c) 2011 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/browser_shutdown.h"
 
 #include <map>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 200 matching lines @@
     switches::RemoveSwitchesForAutostart(&switches);
     // Append the old switches to the new command line.
     for (std::map<std::string, CommandLine::StringType>::const_iterator i =
         switches.begin(); i != switches.end(); ++i) {
       CommandLine::StringType switch_value = i->second;
       if (!switch_value.empty())
         new_cl->AppendSwitchNative(i->first, i->second);
       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();
 #endif  // !defined(OS_CHROMEOS)
   }
 
   if (shutdown_type_ > NOT_VALID && shutdown_num_processes_ > 0) {
     // Measure total shutdown time as late in the process as possible
     // and then write it to a file to be read at startup.
     // We can't use prefs since all services are shutdown at this point.
@@ skipping 84 matching lines @@
 
 bool ShuttingDownWithoutClosingBrowsers() {
   return g_shutting_down_without_closing_browsers;
 }
 
 void SetShuttingDownWithoutClosingBrowsers(bool without_close) {
   g_shutting_down_without_closing_browsers = without_close;
 }
 
 }  // namespace browser_shutdown