Have content/ create and destroy its own threads.

content/browser/browser_main_loop.h

Index: content/browser/browser_main_loop.h
diff --git a/content/browser/browser_main_loop.h b/content/browser/browser_main_loop.h
index 8642e4ff550e40f0be25468c5019fad2cdc11bcc..98f8f370d9d7d17a37b59d9da6302ee91e473b16 100644
--- a/content/browser/browser_main_loop.h
+++ b/content/browser/browser_main_loop.h
@@ -10,6 +10,8 @@
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "content/browser/browser_process_io_thread.h"
+#include "content/browser/browser_process_sub_thread.h"
 
 class CommandLine;
 class HighResolutionTimerManager;
@@ -65,6 +67,14 @@ class BrowserMainLoop {
   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);
 };