Have content/ create and destroy its own threads.

content/browser/browser_main_loop.h

 // 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.
 
 #ifndef CONTENT_BROWSER_BROWSER_MAIN_LOOP_H_
 #define CONTENT_BROWSER_BROWSER_MAIN_LOOP_H_
 #pragma once
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "content/browser/browser_process_sub_thread.h"
 
 class CommandLine;
 class HighResolutionTimerManager;
 class MessageLoop;
 
 namespace base {
 class SystemMonitor;
 }
 
 namespace net {
@@ skipping 35 matching lines @@
   // The BrowserParts fucntions for each part are called in the order added.
   // They are released (destroyed) in the reverse order.
   std::vector<BrowserMainParts*> parts_list_;
 
   // Members initialized in |MainMessageLoopStart()| ---------------------------
   scoped_ptr<MessageLoop> main_message_loop_;
   scoped_ptr<base::SystemMonitor> system_monitor_;
   scoped_ptr<HighResolutionTimerManager> hi_res_timer_manager_;
   scoped_ptr<net::NetworkChangeNotifier> network_change_notifier_;
   scoped_ptr<BrowserThreadImpl> main_thread_;
+  scoped_ptr<BrowserProcessSubThread> io_thread_;
+  scoped_ptr<BrowserProcessSubThread> file_thread_;
+  scoped_ptr<BrowserProcessSubThread> db_thread_;
+  scoped_ptr<BrowserProcessSubThread> process_launcher_thread_;
+  scoped_ptr<BrowserProcessSubThread> cache_thread_;
+#if defined(OS_CHROMEOS)
+  scoped_ptr<BrowserProcessSubThread> web_socket_proxy_thread_;
+#endif
 
   DISALLOW_COPY_AND_ASSIGN(BrowserMainLoop);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BROWSER_MAIN_LOOP_H_