Add WiFi SSID getter to NetworkChangeNotifier.

net/base/network_change_notifier_linux.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 NET_BASE_NETWORK_CHANGE_NOTIFIER_LINUX_H_
 #define NET_BASE_NETWORK_CHANGE_NOTIFIER_LINUX_H_
 
+#include <string>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
 #include "net/base/network_change_notifier.h"
 
 namespace net {
 
 class NET_EXPORT_PRIVATE NetworkChangeNotifierLinux
     : public NetworkChangeNotifier {
  public:
   static NetworkChangeNotifierLinux* Create();
 
  private:
   class Thread;
 
   NetworkChangeNotifierLinux();
   ~NetworkChangeNotifierLinux() override;
   static NetworkChangeCalculatorParams NetworkChangeCalculatorParamsLinux();
 
   // NetworkChangeNotifier:
   ConnectionType GetCurrentConnectionType() const override;
+  std::string GetCurrentWiFiSSID() const override;
 
   const internal::AddressTrackerLinux* GetAddressTrackerInternal()
       const override;
 
   // The thread used to listen for notifications.  This relays the notification
   // to the registered observers without posting back to the thread the object
   // was created on.
   // Also used for DnsConfigService which requires TYPE_IO message loop.
   scoped_ptr<Thread> notifier_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierLinux);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_LINUX_H_