Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/menu_ui/menu_ui.install

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * @file
+ * Install, update and uninstall functions for the menu_ui module.
+ */
+
+/**
+ * Implements hook_install().
+ */
+function menu_ui_install() {
+  // Rebuild all the menu data.
+  // @todo - remove this when we understand why removing it breaks the
+  // standard install profile, possibly need to be handled in
+  // \Drupal\Core\Extension\ModuleHandler::install().
+  // @see https://www.drupal.org/node/2181151
+  \Drupal::service('router.builder')->rebuild();
+}
+
+/**
+ * Implements hook_uninstall().
+ */
+function menu_ui_uninstall() {
+  \Drupal::service('router.builder')->setRebuildNeeded();
+}