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

chrome/browser/ui/ash/system_tray_client.h

Index: chrome/browser/ui/ash/system_tray_client.h
diff --git a/chrome/browser/ui/ash/system_tray_client.h b/chrome/browser/ui/ash/system_tray_client.h
index 9aee553438a53b4155ad296a34c06b5f937823cb..9c97c8db49b7bc7b0830e6ba590e71aeec108278 100644
--- a/chrome/browser/ui/ash/system_tray_client.h
+++ b/chrome/browser/ui/ash/system_tray_client.h
@@ -68,15 +68,12 @@ class SystemTrayClient : public ash::mojom::SystemTrayClient,
   // 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);
 };