Move ProxyConfigService construction onto the IO thread.

net/proxy/proxy_config_service.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 NET_PROXY_PROXY_CONFIG_SERVICE_H_
 #define NET_PROXY_PROXY_CONFIG_SERVICE_H_
 
 #include "net/base/net_export.h"
 
 namespace net {
@@ skipping 43 matching lines @@
   virtual ConfigAvailability GetLatestProxyConfig(ProxyConfig* config) = 0;
 
   // ProxyService will call this periodically during periods of activity.
   // It can be used as a signal for polling-based implementations.
   //
   // Note that this is purely used as an optimization -- polling
   // implementations could simply set a global timer that goes off every
   // X seconds at which point they check for changes. However that has
   // the disadvantage of doing continuous work even during idle periods.
   virtual void OnLazyPoll() {}
+
+
+  // Called on the Glib thread to indicate now is the time for shutdown work

[digit1, 2012/10/19 10:32:46]

Again, this file is not 100% specific to Linux, so please avoid mentioning Glib
here. I also believe there is a policy of not mentioning the UI thread
explicitely in low-level layers like base/ and net/, so maybe talk about the
"main thread" here instead.

+  // that must occur on the Glib thread.  Its also one of the last safe times
+  // to post shutdown tasks to other browser threads.
+  virtual void StartTearDown() {}
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_CONFIG_SERVICE_H_