Allow ProxyConfigService to report "no configuration set"

net/proxy/proxy_config_service_win.h

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// 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_WIN_H_
 #define NET_PROXY_PROXY_CONFIG_SERVICE_WIN_H_
 #pragma once
 
 #include <windows.h>
 #include <winhttp.h>
 
@@ skipping 45 matching lines @@
   void StartWatchingRegistryForChanges();
 
   // Creates a new KeyEntry and appends it to |keys_to_watch_|. If the key
   // fails to be created, it is not appended to the list and we return false.
   bool AddKeyToWatchList(HKEY rootkey, const wchar_t* subkey);
 
   // ObjectWatcher::Delegate methods:
   // This is called whenever one of the registry keys we are watching change.
   virtual void OnObjectSignaled(HANDLE object);
 
-  static void GetCurrentProxyConfig(ProxyConfig* config);
+  static ConfigAvailability GetCurrentProxyConfig(ProxyConfig* config);
 
   // Set |config| using the proxy configuration values of |ie_config|.
   static void SetFromIEConfig(
       ProxyConfig* config,
       const WINHTTP_CURRENT_USER_IE_PROXY_CONFIG& ie_config);
 
   KeyEntryList keys_to_watch_;
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_CONFIG_SERVICE_WIN_H_