chromeos: Introduce SetClient() on ash::mojom::SystemTray interface

chrome/browser/ui/ash/system_tray_client.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 CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CLIENT_H_
 #define CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CLIENT_H_
 
 #include "ash/public/interfaces/system_tray.mojom.h"
 #include "base/macros.h"
 #include "chrome/browser/chromeos/system/system_clock_observer.h"
@@ skipping 50 matching lines @@
   void ShowNetworkCreate(const std::string& type) override;
   void ShowNetworkSettings(const std::string& network_id) override;
   void ShowProxySettings() override;
   void SignOut() override;
   void RequestRestartForUpdate() override;
 
  private:
   // chromeos::system::SystemClockObserver:
   void OnSystemClockChanged(chromeos::system::SystemClock* clock) override;
 
-  // Connects or reconnects the |system_tray_| interface.
-  void ConnectToSystemTray();
-
-  // Handles errors on the |system_tray_| interface connection.
-  void OnClientConnectionError();
-
   // System tray mojo service in ash.
   ash::mojom::SystemTrayPtr system_tray_;
 
+  // Binds this object to the client interface.
+  mojo::Binding<ash::mojom::SystemTrayClient> binding_;
+
   DISALLOW_COPY_AND_ASSIGN(SystemTrayClient);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CLIENT_H_