Reland: chromeos: Convert ash VPNDelegate interface to mojo

ash/mus/system_tray_delegate_mus.h

 // Copyright 2016 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 ASH_MUS_SYSTEM_TRAY_DELEGATE_MUS_H_
 #define ASH_MUS_SYSTEM_TRAY_DELEGATE_MUS_H_
 
 #include <memory>
 
 #include "ash/common/system/tray/default_system_tray_delegate.h"
 #include "base/macros.h"
 
 namespace ash {
 
 class NetworkingConfigDelegate;
-class VPNDelegate;
 
 // Handles the settings displayed in the system tray menu. For the classic ash
 // version see SystemTrayDelegateChromeOS.
 //
 // Chrome OS only. Other platforms use DefaultSystemTrayDelegate directly.
 //
 // TODO: Support all methods in SystemTrayDelegate. http://crbug.com/647412.
 class SystemTrayDelegateMus : public DefaultSystemTrayDelegate {
  public:
   SystemTrayDelegateMus();
   ~SystemTrayDelegateMus() override;
 
  private:
   // SystemTrayDelegate:
   NetworkingConfigDelegate* GetNetworkingConfigDelegate() const override;
-  VPNDelegate* GetVPNDelegate() const override;
 
   std::unique_ptr<NetworkingConfigDelegate> networking_config_delegate_;
-  std::unique_ptr<VPNDelegate> vpn_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayDelegateMus);
 };
 
 }  // namespace ash
 
 #endif  // ASH_MUS_SYSTEM_TRAY_DELEGATE_MUS_H_