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

ash/common/system/tray/system_tray_delegate.h

Index: ash/common/system/tray/system_tray_delegate.h
diff --git a/ash/common/system/tray/system_tray_delegate.h b/ash/common/system/tray/system_tray_delegate.h
index 6c8a20fcb48e60c24d26a5957bea561c4e1eb112..2c19d6d82d186c80b3591e83f0e4abf0458affbe 100644
--- a/ash/common/system/tray/system_tray_delegate.h
+++ b/ash/common/system/tray/system_tray_delegate.h
@@ -51,24 +51,6 @@ struct ASH_EXPORT BluetoothDeviceInfo {
 
 using BluetoothDeviceList = std::vector<BluetoothDeviceInfo>;
 
-struct ASH_EXPORT UpdateInfo {
-  enum UpdateSeverity {
-    UPDATE_NONE,
-    UPDATE_LOW,
-    UPDATE_ELEVATED,
-    UPDATE_HIGH,
-    UPDATE_SEVERE,
-    UPDATE_CRITICAL,
-  };
-
-  UpdateInfo();
-  ~UpdateInfo();
-
-  UpdateSeverity severity;
-  bool update_required;
-  bool factory_reset_required;
-};
-
 class NetworkingConfigDelegate;
 
 // SystemTrayDelegate is intended for delegating tasks in the System Tray to the
@@ -123,9 +105,6 @@ class ASH_EXPORT SystemTrayDelegate {
   // crbug.com/443119
   virtual bool IsUserChild() const;
 
-  // Fills |info| structure (which must not be null) with current update info.
-  virtual void GetSystemUpdateInfo(UpdateInfo* info) const;
-
   // Returns true if settings menu item should appear.
   virtual bool ShouldShowSettings() const;