diff --git a/core/lib/Drupal/Core/Routing/RouteSubscriberBase.php b/core/lib/Drupal/Core/Routing/RouteSubscriberBase.php
new file mode 100644
index 0000000..8860b11
--- /dev/null
+++ b/core/lib/Drupal/Core/Routing/RouteSubscriberBase.php
@@ -0,0 +1,49 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Routing\RouteSubscriberBase
+ */
+
+namespace Drupal\Core\Routing;
+
+use Drupal\Core\Routing\RoutingEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\Routing\RouteCollection;
+
+/**
+ * Provides a base implementation for RouteSubscriber.
+ */
+abstract class RouteSubscriberBase implements EventSubscriberInterface {
+
+  /**
+   * Provides new routes by adding them to the collection.
+   *
+   * Subclasses should use this method and add \Symfony\Component\Routing\Route
+   * objects with $collection->add($route);.
+   *
+   * @param \Symfony\Component\Routing\RouteCollection $collection
+   *   The route collection for adding routes.
+   */
+  abstract public function routes(RouteCollection $collection);
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    $events[RoutingEvents::DYNAMIC] = 'getRoutes';
+    return $events;
+  }
+
+  /**
+   * Delegates the route gathering to self::routes().
+   *
+   * @param \Drupal\Core\Routing\RouteBuildEvent $event
+   *   The route build event.
+   */
+  public function getRoutes(RouteBuildEvent $event) {
+    $collection = $event->getRouteCollection();
+    $this->routes($collection);
+  }
+
+}
diff --git a/core/modules/comment/lib/Drupal/comment/Routing/RouteSubscriber.php b/core/modules/comment/lib/Drupal/comment/Routing/RouteSubscriber.php
index 354af6f..5547483 100644
--- a/core/modules/comment/lib/Drupal/comment/Routing/RouteSubscriber.php
+++ b/core/modules/comment/lib/Drupal/comment/Routing/RouteSubscriber.php
@@ -7,16 +7,15 @@
 
 namespace Drupal\comment\Routing;
 
-use Drupal\Core\Routing\RouteBuildEvent;
-use Drupal\Core\Routing\RoutingEvents;
-use Symfony\Component\EventDispatcher\EventSubscriberInterface;
-use Symfony\Component\Routing\Route;
 use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Routing\RouteSubscriberBase;
+use Symfony\Component\Routing\Route;
+use Symfony\Component\Routing\RouteCollection;
 
 /**
  * Defines a route subscriber for the comment module.
  */
-class RouteSubscriber implements EventSubscriberInterface {
+class RouteSubscriber extends RouteSubscriberBase {
 
   /**
    * The module handler service.
@@ -38,19 +37,8 @@ public function __construct(ModuleHandlerInterface $module_handler) {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
-    $events[RoutingEvents::DYNAMIC] = 'routes';
-    return $events;
-  }
-
-  /**
-   * If node module is present, adds the legacy /comment/{node}/reply route.
-   *
-   * @param \Drupal\Core\Routing\RouteBuildEvent $event
-   *   The route build event.
-   */
-  public function routes(RouteBuildEvent $event) {
-    $collection = $event->getRouteCollection();
+  public function routes(RouteCollection $collection) {
+    // If node module is present, adds the legacy /comment/{node}/reply route.
     if ($this->moduleHandler->moduleExists('node')) {
       $route = new Route(
         "/comment/{node}/reply",