diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 4927fcc..d8407b1 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -9,7 +9,7 @@
 use Drupal\Core\Database\Install\TaskException;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageManager;
-use Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationBrowser;
+use Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationBrowser;
 use Drupal\Core\StringTranslation\Translator\FileTranslation;
 
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -356,11 +356,13 @@ function install_begin_request(&$install_state) {
   else {
     // @todo Move into a proper Drupal\Core\DependencyInjection\InstallContainerBuilder.
     $container = new ContainerBuilder();
-
+    // Register Core's namespaces just for the installer.
     $namespaces = array(
       'Drupal\Core' => DRUPAL_ROOT . '/core/lib',
       'Drupal\Component' => DRUPAL_ROOT . '/core/lib',
     );
+    $container->register('container.namespaces', 'ArrayObject')
+      ->addArgument('%container.namespaces%');
     $container->setParameter('container.namespaces', $namespaces);
 
     $container->register('event_dispatcher', 'Symfony\Component\EventDispatcher\EventDispatcher');
@@ -379,7 +381,7 @@ function install_begin_request(&$install_state) {
 
     // Register the 'language_manager' service.
     $container->register('plugin.manager.language_negotiation_method', 'Drupal\Core\Language\LanguageNegotiationMethodManager')
-      ->addArgument('%container.namespaces%');
+      ->addArgument(new Reference('container.namespaces'));
     $container->register('language_manager', 'Drupal\Core\Language\LanguageManager')
       ->addArgument(array())
       ->addArgument(new Reference('plugin.manager.language_negotiation_method'));
diff --git a/core/lib/Drupal/Core/CoreBundle.php b/core/lib/Drupal/Core/CoreBundle.php
index 8dbbecd..f95f918 100644
--- a/core/lib/Drupal/Core/CoreBundle.php
+++ b/core/lib/Drupal/Core/CoreBundle.php
@@ -135,9 +135,10 @@ protected function registerLanguage(ContainerBuilder $container) {
 
     // Register the 'language_manager' service.
     $container->register('plugin.manager.language_negotiation_method', 'Drupal\Core\Language\LanguageNegotiationMethodManager')
-      ->addArgument('%container.namespaces%');
+      ->addArgument(new Reference('container.namespaces'));
     $container->register('language_manager', 'Drupal\Core\Language\LanguageManager')
       ->addArgument($config)
       ->addArgument(new Reference('plugin.manager.language_negotiation_method'));
    }
+
 }
diff --git a/core/lib/Drupal/Core/Language/LanguageManager.php b/core/lib/Drupal/Core/Language/LanguageManager.php
index 417fa72..760be41 100644
--- a/core/lib/Drupal/Core/Language/LanguageManager.php
+++ b/core/lib/Drupal/Core/Language/LanguageManager.php
@@ -74,13 +74,13 @@ class LanguageManager {
    *
    * @param array $config
    *   An array of configuration.
-   * @param PluginManagerInterface $negotiatorManager
+   * @param PluginManagerInterface $negotiator_manager
    *   An object that implements PluginManagerInterface interface
    *   for language negotiation.
    */
-  public function __construct(array $config, PluginManagerInterface $negotiatorManager) {
+  public function __construct(array $config, PluginManagerInterface $negotiator_manager) {
     $this->config = $config;
-    $this->negotiatorManager = $negotiatorManager;
+    $this->negotiatorManager = $negotiator_manager;
   }
 
   /**
@@ -140,8 +140,8 @@ public function getLanguage($type) {
       // happening during initialization will return the original strings which
       // can be translated by calling t() again afterwards. This can happen for
       // instance while parsing negotiation method definitions.
-      elseif ($type == LANGUAGE_TYPE_INTERFACE) {
-        return new Language(array('langcode' => LANGUAGE_SYSTEM));
+      elseif ($type == Language::TYPE_INTERFACE) {
+        return new Language(array('langcode' => Language::LANGCODE_SYSTEM));
       }
     }
 
@@ -284,13 +284,13 @@ public function getLanguageDefault() {
    *
    * @param $flags
    *   (optional) Specifies the state of the languages that have to be returned.
-   *   It can be: LANGUAGE_CONFIGURABLE, LANGUAGE_LOCKED, LANGUAGE_ALL.
+   *   It can be: Language::STATE_CONFIGURABLE, Language::STATE_LOCKED, Language::STATE_ALL.
    *
    * @return array
    *   An associative array of languages, keyed by the language code, ordered by
    *   weight ascending and name ascending.
    */
-  function getLanguageList($flags = LANGUAGE_CONFIGURABLE) {
+  public function getLanguageList($flags = Language::STATE_CONFIGURABLE) {
     // Initialize master language list.
     if (!isset($this->languageList)) {
       // Initialize local language list cache.
@@ -300,7 +300,7 @@ function getLanguageList($flags = LANGUAGE_CONFIGURABLE) {
       $default = $this->getLanguageDefault();
       // @todo Make this method part of a language manager instance provided by
       //   the Language module.
-      if ($this->isMultilingual() || Drupal::moduleHandler()->moduleExists('language')) {
+      if ($this->isMultilingual() || \Drupal::moduleHandler()->moduleExists('language')) {
         // Use language module configuration if available.
         $this->languageList = db_query('SELECT * FROM {language} ORDER BY weight ASC, name ASC')->fetchAllAssoc('langcode', \PDO::FETCH_ASSOC);
 
@@ -325,7 +325,7 @@ function getLanguageList($flags = LANGUAGE_CONFIGURABLE) {
     $filtered_languages = array();
 
     // Add the site's default language if flagged as allowed value.
-    if ($flags & LANGUAGE_SITE_DEFAULT) {
+    if ($flags & Language::STATE_SITE_DEFAULT) {
       $default = isset($default) ? $default : $this->getLanguageDefault();
       // Rename the default language.
       $default->name = t("Site's default language (@lang_name)", array('@lang_name' => $default->name));
@@ -333,9 +333,9 @@ function getLanguageList($flags = LANGUAGE_CONFIGURABLE) {
     }
 
     foreach ($this->languageList as $langcode => $language) {
-      if (($language->locked && !($flags & LANGUAGE_LOCKED)) || (!$language->locked && !($flags & LANGUAGE_CONFIGURABLE))) {
+      if (($language->locked && !($flags & Language::STATE_LOCKED)) || (!$language->locked && !($flags & Language::STATE_CONFIGURABLE))) {
         continue;
-       }
+      }
       $filtered_languages[$langcode] = $language;
     }
 
@@ -361,14 +361,14 @@ public function getDefaultLockedLanguages($weight = 0) {
       'enabled' => TRUE,
     );
 
-    $languages[LANGUAGE_NOT_SPECIFIED] = new Language(array(
-      'langcode' => LANGUAGE_NOT_SPECIFIED,
+    $languages[Language::LANGCODE_NOT_SPECIFIED] = new Language(array(
+      'langcode' => Language::LANGCODE_NOT_SPECIFIED,
       'name' => t('Not specified'),
       'weight' => ++$weight,
     ) + $locked_language);
 
-    $languages[LANGUAGE_NOT_APPLICABLE] = new Language(array(
-      'langcode' => LANGUAGE_NOT_APPLICABLE,
+    $languages[Language::LANGCODE_NOT_APPLICABLE] = new Language(array(
+      'langcode' => Language::LANGCODE_NOT_APPLICABLE,
       'name' => t('Not applicable'),
       'weight' => ++$weight,
     ) + $locked_language);
diff --git a/core/lib/Drupal/Core/Language/LanguageNegotiationMethodManager.php b/core/lib/Drupal/Core/Language/LanguageNegotiationMethodManager.php
index 665830c..8cbf5e8 100644
--- a/core/lib/Drupal/Core/Language/LanguageNegotiationMethodManager.php
+++ b/core/lib/Drupal/Core/Language/LanguageNegotiationMethodManager.php
@@ -8,7 +8,7 @@
 namespace Drupal\Core\Language;
 
 use Drupal\Component\Plugin\PluginManagerBase;
-use Drupal\Component\Plugin\Factory\DefaultFactory;
+use Drupal\Core\Plugin\Factory\ContainerFactory;
 use Drupal\Core\Plugin\Discovery\AnnotatedClassDiscovery;
 use Drupal\Core\Plugin\Discovery\CacheDecorator;
 
@@ -20,13 +20,15 @@ class LanguageNegotiationMethodManager extends PluginManagerBase {
   /**
    * Constructs a new LanguageNegotiationMethodManager object.
    *
-   * @param array $namespaces
-   *   An array of namespaces to discover.
+   * @param \Traversable $namespaces
+   *   An object that implements \Traversable which contains the root paths
+   *   keyed by the corresponding namespace to look for plugin implementations.
    */
-  public function __construct(array $namespaces) {
-    $this->discovery = new AnnotatedClassDiscovery('Core', 'LanguageNegotiation', $namespaces);
+  public function __construct($namespaces) {
+    $this->discovery = new AnnotatedClassDiscovery('LanguageNegotiation', $namespaces);
     $this->discovery = new CacheDecorator($this->discovery, 'language_negotiation_plugins');
-    $this->factory = new DefaultFactory($this->discovery);
+
+    $this->factory = new ContainerFactory($this);
   }
 
 }
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationBrowser.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php
similarity index 97%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationBrowser.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php
index 83db7dd..4f9d00d 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationBrowser.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationBrowser.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationBrowser.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationSelected.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationSelected.php
similarity index 82%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationSelected.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationSelected.php
index b578fb8..f6625b1 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationSelected.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationSelected.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationSelected.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationSelected.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
@@ -31,7 +31,7 @@ class LanguageNegotiationSelected extends LanguageNegotiationMethodBase {
   const METHOD_ID = 'language-selected';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
     // Replace the site's default langcode by its real value.
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationSession.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationSession.php
similarity index 85%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationSession.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationSession.php
index 7d4491e..3fb04ce 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationSession.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationSession.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationSession.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationSession.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
@@ -31,7 +31,7 @@ class LanguageNegotiationSession extends LanguageNegotiationMethodBase {
   const METHOD_ID = 'language-session';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
     $param = $this->config['session']['parameter'];
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUI.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUI.php
similarity index 68%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUI.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUI.php
index 869ccf5..6dfc71c 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUI.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUI.php
@@ -2,13 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationUI.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationUI.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
+use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageNegotiationMethodBase;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -17,7 +18,7 @@
  *
  * @Plugin(
  *   id = LanguageNegotiationUI::METHOD_ID,
- *   types = {LANGUAGE_TYPE_CONTENT},
+ *   types = {Language::TYPE_CONTENT},
  *   weight = 9,
  *   name = @Translation("Interface"),
  *   description = @Translation("Use the detected interface language.")
@@ -31,10 +32,10 @@ class LanguageNegotiationUI extends LanguageNegotiationMethodBase {
   const METHOD_ID = 'language-interface';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
-    return $this->languageManager->getLanguage(LANGUAGE_TYPE_INTERFACE)->langcode;
+    return $this->languageManager->getLanguage(Language::TYPE_INTERFACE)->langcode;
   }
 
 }
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUrl.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
similarity index 92%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUrl.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
index d0eba9f..a0f3d65 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUrl.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationUrl.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationUrl.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
@@ -41,7 +41,7 @@ class LanguageNegotiationUrl extends LanguageNegotiationMethodBase {
   const CONFIG_DOMAIN = 'domain';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
     if (!$request) {
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUrlFallback.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUrlFallback.php
similarity index 88%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUrlFallback.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUrlFallback.php
index 17bb549..7da29a2 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUrlFallback.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUrlFallback.php
@@ -2,13 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationUrlFallback.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationUrlFallback.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
+use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageManager;
 use Drupal\Core\Language\LanguageNegotiationMethodBase;
 use Symfony\Component\HttpFoundation\Request;
@@ -37,7 +38,7 @@
  *
  * @Plugin(
  *   id = LanguageNegotiationUrlFallback::METHOD_ID,
- *   types = {LANGUAGE_TYPE_URL},
+ *   types = {Language::TYPE_URL},
  *   weight = 8,
  *   name = @Translation("URL fallback"),
  *   description = @Translation("Use an already detected language for URLs if none is found..")
@@ -51,7 +52,7 @@ class LanguageNegotiationUrlFallback extends LanguageNegotiationMethodBase {
   const METHOD_ID = 'language-url-fallback';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
     $default = $this->languageManager->getLanguageDefault();
@@ -66,7 +67,7 @@ public function negotiateLanguage(array $languages, Request $request = NULL) {
       return $default->langcode;
     }
     else {
-      return $this->languageManager->getLanguage(LANGUAGE_TYPE_INTERFACE)->langcode;
+      return $this->languageManager->getLanguage(Language::TYPE_INTERFACE)->langcode;
     }
   }
 
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUser.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUser.php
similarity index 81%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUser.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUser.php
index b641759..ba9741d 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUser.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUser.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationUrl.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationUrl.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
@@ -30,7 +30,7 @@ class LanguageNegotiationUser extends LanguageNegotiationMethodBase {
   const METHOD_ID = 'language-user';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
     // User preference (only for authenticated users).
diff --git a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUserAdmin.php b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php
similarity index 82%
rename from core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUserAdmin.php
rename to core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php
index 67fde9d..0f2d7a0 100644
--- a/core/lib/Drupal/Core/Plugin/Core/LanguageNegotiation/LanguageNegotiationUserAdmin.php
+++ b/core/lib/Drupal/Core/Language/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php
@@ -2,13 +2,14 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationUserAdmin.
+ * Contains \Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationUserAdmin.
  */
 
-namespace Drupal\Core\Plugin\Core\LanguageNegotiation;
+namespace Drupal\Core\Language\Plugin\LanguageNegotiation;
 
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
+use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageNegotiationMethodBase;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -17,7 +18,7 @@
  *
  * @Plugin(
  *   id = LanguageNegotiationUserAdmin::METHOD_ID,
- *   types = {LANGUAGE_TYPE_INTERFACE},
+ *   types = {Language::TYPE_INTERFACE},
  *   weight = 10,
  *   name = @Translation("Account administration pages"),
  *   description = @Translation("Account administration pages language setting.")
@@ -31,7 +32,7 @@ class LanguageNegotiationUserAdmin extends LanguageNegotiationMethodBase {
   const METHOD_ID = 'language-user-admin';
 
   /**
-   * Implements \Drupal\Core\Language\LanguageNegotiationInterface::negotiateLanguage().
+   * {@inheritdoc}
    */
   public function negotiateLanguage(array $languages, Request $request = NULL) {
     // User preference (only for authenticated users).
diff --git a/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php b/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php
index 3b47b57..ea9555a 100644
--- a/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php
+++ b/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php
@@ -96,7 +96,7 @@ public function processOutbound($path, &$options = array(), Request $request = N
       $url_scheme = $request->getScheme();
       $port = $request->getPort();
     }
-    $languages = array_flip(array_keys($this->languages));
+    $languages = array_flip(array_keys($this->languageManager->getLanguageList()));
     // Language can be passed as an option, or we go for current URL language.
     if (!isset($options['language'])) {
       $language_url = $this->languageManager->getLanguage(Language::TYPE_URL);
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php
index 2974c3d..2c5b529 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php
@@ -9,7 +9,7 @@
 
 use Drupal\simpletest\WebTestBase;
 use Drupal\Core\Language\Language;
-use Drupal\Core\Plugin\Core\LanguageNegotiation\LanguageNegotiationBrowser;
+use Drupal\Core\Language\Plugin\LanguageNegotiation\LanguageNegotiationBrowser;
 use Symfony\Component\HttpFoundation\Request;
 
 /**