Move the HTML request type handling to a subscriber class so that it's nicely encapsulated.

core/lib/Drupal/Core/DrupalApp.php

@@ -14,6 +14,8 @@
 use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
 
+use Drupal\Core\EventSubscriber\HtmlSubscriber;
+
 use Exception;
 
 /**
@@ -32,21 +34,8 @@ function execute(Request $request) {
 
       $dispatcher = new EventDispatcher();
 
-      // Quick and dirty attempt at wrapping our rendering logic as is.
-      $dispatcher->addListener(KernelEvents::VIEW, function(Event $event) {
-        $page_callback_result = $event->getControllerResult();
-        $event->setResponse(new Response(drupal_render_page($page_callback_result)));
-      });
-      $dispatcher->addListener(KernelEvents::EXCEPTION, function(Event $event) use ($request) {
-        debug($request->getAcceptableContentTypes());
-
-        if (in_array('text/html', $request->getAcceptableContentTypes())) {
-          if ($event->getException() instanceof ResourceNotFoundException) {
-            $event->setResponse(new Response('Not Found', 404));
-          }
-        }
-      });
-
+      // @todo Make this extensible rather than just hard coding some.
+      $dispatcher->addSubscriber(new HtmlSubscriber());
 
       // Resolve a routing context(path, etc) using the routes object to a
       // Set a routing context to translate.
@@ -65,7 +54,7 @@ function execute(Request $request) {
       $response = $kernel->handle($request);
     }
     catch (Exception $e) {
-      $error_event = new GetResponseForExceptionEvent($this, $request, $this->type, $e);
+      $error_event = new GetResponseForExceptionEvent($kernel, $request, HttpKernelInterface::MASTER_REQUEST, $e);
       $dispatcher->dispatch(KernelEvents::EXCEPTION, $error_event);
       if ($error_event->hasResponse()) {
         $response = $error_event->getResponse();

core/lib/Drupal/Core/EventSubscriber/HtmlSubscriber.php

+<?php
+
+namespace Drupal\Core\EventSubscriber;
+
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\EventDispatcher\Event;
+use Symfony\Component\HttpKernel\Event\GetResponseEvent;
+use Symfony\Component\Routing\Exception\ResourceNotFoundException;
+
+/**
+ * @file
+ *
+ * Description goes here.
+ */
+
+/**
+ * Description of HtmlSubscriber
+ */
+class HtmlSubscriber implements EventSubscriberInterface {
+
+  protected function isHtmlRequestEvent(GetResponseEvent $event) {
+    return in_array('text/html', $event->getRequest()->getAcceptableContentTypes());
+  }
+
+  public function onResourceNotFoundException(GetResponseEvent $event) {
+    if ($this->isHtmlRequestEvent($event) && $event->getException() instanceof ResourceNotFoundException) {
+      $event->setResponse(new Response('Not Found', 404));
+    }
+  }
+
+  public function onView(GetResponseEvent $event) {
+    if ($this->isHtmlRequestEvent($event)) {
+      $page_callback_result = $event->getControllerResult();
+      $event->setResponse(new Response(drupal_render_page($page_callback_result)));
+    }
+  }
+
+  public function onAccessDeniedException(Event $event) {
+
+  }
+
+  static function getSubscribedEvents() {
+    $events[KernelEvents::EXCEPTION][] = array('onResourceNotFoundException');
+    $events[KernelEvents::EXCEPTION][] = array('onAccessDeniedException');
+
+    $events[KernelEvents::VIEW][] = array('onView');
+
+    return $events;
+  }
+}