diff -u b/core/lib/Drupal/Core/Extension/ModuleInstaller.php b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
--- b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
@@ -18,11 +18,10 @@
 use Drupal\Core\DependencyInjection\UpdateDependenciesTrait;
 use Drupal\Core\DrupalKernelInterface;
 use Drupal\Component\Utility\SafeMarkup;
-use Drupal\Component\Utility\String;
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\KeyValueStore\KeyValueFactoryInterface;
 use Drupal\Core\Plugin\CachedDiscoveryClearer;
-use Drupal\Core\Routing\RouteBuilderIndicatorInterface;
+use Drupal\Core\Routing\RouteBuilderInterface;
 use Drupal\Core\StreamWrapper\StreamWrapperManager;
 use Psr\Log\LoggerInterface;

@@ -86,11 +85,11 @@
   protected $pluginCacheClearer;

   /**
-   * The route rebuild indicator.
+   * The route builder.
    *
-   * @var \Drupal\Core\Routing\RouteBuilderIndicatorInterface
+   * @var \Drupal\Core\Routing\RouteBuilderInterface
    */
-  protected $routeRebuildIndicator;
+  protected $routeBuilder;

   /**
    * The entity manager.
@@ -149,8 +148,8 @@
    *   The config installer.
    * @param \Drupal\Core\Plugin\CachedDiscoveryClearer $plugin_cache_clearer
    *   The plugin cache clearer.
-   * @param \Drupal\Core\Routing\RouteBuilderIndicatorInterface $route_rebuild_indicator
-   *   The route rebuild indicator.
+   * @param \Drupal\Core\Routing\RouteBuilderInterface $route_builder
+   *   The route builder.
    * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
    *   The entity manager.
    * @param \Drupal\Core\StreamWrapper\StreamWrapperManager $stream_wrapper_manager
@@ -167,14 +166,14 @@
    * @see \Drupal\Core\DrupalKernel
    * @see \Drupal\Core\CoreServiceProvider
    */
-  public function __construct($root, ModuleHandlerInterface $module_handler, DrupalKernelInterface $kernel, ConfigFactoryInterface $config_factory, ConfigInstallerInterface $config_installer, CachedDiscoveryClearer $plugin_cache_clearer, RouteBuilderIndicatorInterface $route_rebuild_indicator, EntityManagerInterface $entity_manager, StreamWrapperManager $stream_wrapper_manager, ThemeHandlerInterface $theme_handler, LoggerInterface $logger, ConfigManagerInterface $config_manager, KeyValueFactoryInterface $key_value_factory) {
+  public function __construct($root, ModuleHandlerInterface $module_handler, DrupalKernelInterface $kernel, ConfigFactoryInterface $config_factory, ConfigInstallerInterface $config_installer, CachedDiscoveryClearer $plugin_cache_clearer, RouteBuilderInterface $route_builder, EntityManagerInterface $entity_manager, StreamWrapperManager $stream_wrapper_manager, ThemeHandlerInterface $theme_handler, LoggerInterface $logger, ConfigManagerInterface $config_manager, KeyValueFactoryInterface $key_value_factory) {
     $this->root = $root;
     $this->moduleHandler = $module_handler;
     $this->kernel = $kernel;
     $this->configFactory = $config_factory;
     $this->configInstaller = $config_installer;
     $this->pluginCacheClearer = $plugin_cache_clearer;
-    $this->routeRebuildIndicator = $route_rebuild_indicator;
+    $this->routeBuilder = $route_builder;
     $this->entityManager = $entity_manager;
     $this->streamWrapperManager = $stream_wrapper_manager;
     $this->themeHandler = $theme_handler;
@@ -339,7 +338,7 @@

         // Clear plugin manager caches and flag router to rebuild if requested.
         $this->pluginCacheClearer->clearCachedDefinitions();
-        $this->routeRebuildIndicator->setRebuildNeeded();
+        $this->routeBuilder->setRebuildNeeded();

         // Set the schema version to the number of the last update provided by
         // the module, or the minimum core schema version.
@@ -408,7 +407,7 @@

     // If any modules were newly installed, invoke hook_modules_installed().
     if (!empty($modules_installed)) {
-      \Drupal::service('router.builder')->setRebuildNeeded();
+      $this->routeBuilder->setRebuildNeeded();
       $this->moduleHandler->invokeAll('modules_installed', array($modules_installed));
     }

@@ -533,7 +532,7 @@

       // Clear plugin manager caches and flag router to rebuild if requested.
       $this->pluginCacheClearer->clearCachedDefinitions();
-      $this->routeRebuildIndicator->setRebuildNeeded();
+      $this->routeBuilder->setRebuildNeeded();

       // Update the kernel to exclude the uninstalled modules.
       $this->updateKernel($module_filenames);
@@ -548,7 +547,7 @@

       $this->keyValueFactory->get('system.schema')->delete($module);
     }
-    \Drupal::service('router.builder')->setRebuildNeeded();
+    $this->routeBuilder->setRebuildNeeded();
     drupal_get_installed_schema_version(NULL, TRUE);

     // Let other modules react.