Move ProxyConfigService construction onto the IO thread.

chrome/browser/net/pref_proxy_config_tracker_impl.h

 // Copyright (c) 2012 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 CHROME_BROWSER_NET_PREF_PROXY_CONFIG_TRACKER_IMPL_H_
 #define CHROME_BROWSER_NET_PREF_PROXY_CONFIG_TRACKER_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 23 matching lines @@
   virtual ~ChromeProxyConfigService();
 
   // ProxyConfigService implementation:
   virtual void AddObserver(
       net::ProxyConfigService::Observer* observer) OVERRIDE;
   virtual void RemoveObserver(
       net::ProxyConfigService::Observer* observer) OVERRIDE;
   virtual ConfigAvailability GetLatestProxyConfig(
       net::ProxyConfig* config) OVERRIDE;
   virtual void OnLazyPoll() OVERRIDE;
+  virtual void StartTearDown() OVERRIDE;
 
   // Method on IO thread that receives the preference proxy settings pushed from
   // PrefProxyConfigTrackerImpl.
   void UpdateProxyConfig(ProxyPrefs::ConfigState config_state,
                          const net::ProxyConfig& config);
 
  private:
   // ProxyConfigService::Observer implementation:
   virtual void OnProxyConfigChanged(const net::ProxyConfig& config,
                                     ConfigAvailability availability) OVERRIDE;
@@ skipping 102 matching lines @@
 
   PrefService* pref_service_;
   ChromeProxyConfigService* chrome_proxy_config_service_;  // Weak ptr.
   bool update_pending_;  // True if config has not been pushed to network stack.
   scoped_ptr<PrefSetObserver> proxy_prefs_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefProxyConfigTrackerImpl);
 };
 
 #endif  // CHROME_BROWSER_NET_PREF_PROXY_CONFIG_TRACKER_IMPL_H_