ash: Use system tray mojo interface to show system update tray icon

ash/common/system/tray/system_tray_controller.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_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_CONTROLLER_H_
 #define ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/public/interfaces/system_tray.mojom.h"
 #include "base/compiler_specific.h"
@@ skipping 38 matching lines @@
   void ShowNetworkCreate(const std::string& type);
   void ShowThirdPartyVpnCreate(const std::string& extension_id);
   void ShowNetworkSettings(const std::string& network_id);
   void ShowProxySettings();
   void SignOut();
   void RequestRestartForUpdate();
 
   // Binds the mojom::SystemTray interface to this object.
   void BindRequest(mojom::SystemTrayRequest request);
 
- private:
-  // mojom::SystemTray:
+  // mojom::SystemTray overrides. Public for testing.
   void SetClient(mojom::SystemTrayClientPtr client) override;
   void SetUse24HourClock(bool use_24_hour) override;
+  void ShowUpdateIcon(mojom::UpdateSeverity severity,
+                      bool factory_reset_required) override;
 
+ private:
   // Client interface in chrome browser. Only bound on Chrome OS.
   mojom::SystemTrayClientPtr system_tray_client_;
 
   // Bindings for the SystemTray interface.
   mojo::BindingSet<mojom::SystemTray> bindings_;
 
   // The type of clock hour display: 12 or 24 hour.
   base::HourClockType hour_clock_type_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayController);
 };
 
 }  // namspace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_CONTROLLER_H_