Reland of Use shared NotificationControlButtonsView for non-arc notification buttons

ui/message_center/views/notification_control_buttons_view.cc

Index: ui/message_center/views/notification_control_buttons_view.cc
diff --git a/ui/message_center/views/notification_control_buttons_view.cc b/ui/message_center/views/notification_control_buttons_view.cc
index 5d71a107121365eff17a93f4ab10fef8792b26d1..2db5a2def9fb628d8f33b44d2a05131dc6becdd5 100644
--- a/ui/message_center/views/notification_control_buttons_view.cc
+++ b/ui/message_center/views/notification_control_buttons_view.cc
@@ -80,7 +80,7 @@
     // Add the button at the first.
     DCHECK_LE(child_count(), 1);
     AddChildViewAt(settings_button_, 0);
-  } else if (!show && close_button_) {
+  } else if (!show && settings_button_) {
     RemoveChildView(settings_button_);
     settings_button_ = nullptr;
   }