Remove unused method in the native display service

chrome/browser/notifications/native_notification_display_service.cc

Index: chrome/browser/notifications/native_notification_display_service.cc
diff --git a/chrome/browser/notifications/native_notification_display_service.cc b/chrome/browser/notifications/native_notification_display_service.cc
index 2ffcd75fd3929c32998c54c28a73145fdbef9796..e791a8e1175a9a2ba1ec3451862f338494836a1d 100644
--- a/chrome/browser/notifications/native_notification_display_service.cc
+++ b/chrome/browser/notifications/native_notification_display_service.cc
@@ -171,11 +171,6 @@ void NativeNotificationDisplayService::AddNotificationHandler(
   notification_handlers_[notification_type] = std::move(handler);
 }
 
-void NativeNotificationDisplayService::RemoveNotificationHandler(
-    NotificationCommon::Type notification_type) {
-  notification_handlers_.erase(notification_type);
-}
-
 NotificationHandler* NativeNotificationDisplayService::GetNotificationHandler(
     NotificationCommon::Type notification_type) {
   DCHECK(notification_handlers_.find(notification_type) !=