Reland: chromeos: Convert ash VPNDelegate interface to mojo

ash/mus/system_tray_delegate_mus.h

Index: ash/mus/system_tray_delegate_mus.h
diff --git a/ash/mus/system_tray_delegate_mus.h b/ash/mus/system_tray_delegate_mus.h
index c6768705296d2b5a8ba708b3f19dd6949234e992..87b189f44523f89b5dea2a97c1c63b7283f99493 100644
--- a/ash/mus/system_tray_delegate_mus.h
+++ b/ash/mus/system_tray_delegate_mus.h
@@ -13,7 +13,6 @@
 namespace ash {
 
 class NetworkingConfigDelegate;
-class VPNDelegate;
 
 // Handles the settings displayed in the system tray menu. For the classic ash
 // version see SystemTrayDelegateChromeOS.
@@ -29,10 +28,8 @@ class SystemTrayDelegateMus : public DefaultSystemTrayDelegate {
  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);
 };