Have content/ create and destroy its own threads.

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 95 matching lines @@
       ++shutdown_num_processes_slow_;
   }
 }
 
 FilePath GetShutdownMsPath() {
   FilePath shutdown_ms_file;
   PathService::Get(chrome::DIR_USER_DATA, &shutdown_ms_file);
   return shutdown_ms_file.AppendASCII(kShutdownMsFile);
 }
 
-void Shutdown() {
+bool ShutdownPreThreadsStop() {
 #if defined(OS_CHROMEOS)
   chromeos::BootTimesLoader::Get()->AddLogoutTimeMarker(
       "BrowserShutdownStarted", false);
 #endif
   // During shutdown we will end up some blocking operations.  But the
   // work needs to get done and we're going to wait for them no matter
   // what thread they're on, so don't worry about it slowing down
   // shutdown.
   base::ThreadRestrictions::SetIOAllowed(true);
 
@@ skipping 27 matching lines @@
   }
 
   prefs->SavePersistentPrefs();
 
 #if defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
   // Cleanup any statics created by RLZ. Must be done before NotificationService
   // is destroyed.
   RLZTracker::CleanupRlz();
 #endif
 
+  return restart_last_session;
+}
+
+void ShutdownPostThreadsStop(bool restart_last_session) {
   // The jank'o'meter requires that the browser process has been destroyed
   // before calling UninstallJankometer().
   delete g_browser_process;
   g_browser_process = NULL;
 
   // crbug.com/95079 - This needs to happen after the browser process object
   // goes away.
   ProfileManager::NukeDeletedProfilesFromDisk();
 
 #if defined(OS_CHROMEOS)
@@ skipping 140 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