Add update available icon in system tray

ash/system/tray/system_tray_controller.h

Index: ash/system/tray/system_tray_controller.h
diff --git a/ash/system/tray/system_tray_controller.h b/ash/system/tray/system_tray_controller.h
index 74e5268a057711aa054d3e016919c15d76cc604f..5417a2629dc9b5bc2d1acc0182557c7a9e953c8c 100644
--- a/ash/system/tray/system_tray_controller.h
+++ b/ash/system/tray/system_tray_controller.h
@@ -41,6 +41,7 @@ class ASH_EXPORT SystemTrayController
                                   bool paired,
                                   bool connected);
   void ShowDateSettings();
+  void ShowAboutChromeOS();
   void ShowSetTimeDialog();
   void ShowDisplaySettings();
   void ShowPowerSettings();
@@ -60,6 +61,7 @@ class ASH_EXPORT SystemTrayController
   void ShowProxySettings();
   void SignOut();
   void RequestRestartForUpdate();
+  void RequestUpdateCheck();
 
   // Binds the mojom::SystemTray interface to this object.
   void BindRequest(mojom::SystemTrayRequest request);
@@ -74,6 +76,7 @@ class ASH_EXPORT SystemTrayController
   void ShowUpdateIcon(mojom::UpdateSeverity severity,
                       bool factory_reset_required,
                       mojom::UpdateType update_type) override;
+  void ShowUpdateOverCellularAvailableIcon() override;
 
  private:
   // Client interface in chrome browser. May be null in tests.