Allow ProxyConfigService to report "no configuration set"

net/proxy/proxy_config_service_linux.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_LINUX_H_
 #define NET_PROXY_PROXY_CONFIG_SERVICE_LINUX_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 126 matching lines @@
     // Handler for gconf change notifications: fetches a new proxy
     // configuration from gconf settings, and if this config is
     // different than what we had before, posts a task to have it
     // stored in cached_config_.
     // Left public for simplicity.
     void OnCheckProxyConfigSettings();
 
     // Called from IO thread.
     void AddObserver(Observer* observer);
     void RemoveObserver(Observer* observer);
-    bool GetLatestProxyConfig(ProxyConfig* config);
+    ProxyConfigService::ConfigAvailability GetLatestProxyConfig(
+        ProxyConfig* config);
 
     // Posts a call to OnDestroy() to the UI thread. Called from
     // ProxyConfigServiceLinux's destructor.
     void PostDestroyTask();
     // Safely stops gconf notifications. Posted to the UI thread.
     void OnDestroy();
 
    private:
     friend class base::RefCountedThreadSafe<Delegate>;
 
@@ skipping 74 matching lines @@
                                           file_loop);
   }
   void OnCheckProxyConfigSettings() {
     delegate_->OnCheckProxyConfigSettings();
   }
 
   // ProxyConfigService methods:
   // Called from IO thread.
   virtual void AddObserver(Observer* observer);
   virtual void RemoveObserver(Observer* observer);
-  virtual bool GetLatestProxyConfig(ProxyConfig* config);
+  virtual ProxyConfigService::ConfigAvailability GetLatestProxyConfig(
+      ProxyConfig* config);
 
  private:
   scoped_refptr<Delegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyConfigServiceLinux);
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_CONFIG_SERVICE_LINUX_H_