diff --git a/core/authorize.php b/core/authorize.php
index e880d34..114dcd3 100644
--- a/core/authorize.php
+++ b/core/authorize.php
@@ -80,9 +80,9 @@ function authorize_access_allowed() {
 // display errors via the maintenance theme.
 $module_list['system'] = 'core/modules/system/system.module';
 $module_list['user'] = 'core/modules/user/user.module';
-drupal_container()->get('extension_handler')->setModuleList($module_list);
-drupal_container()->get('extension_handler')->loadModule('system');
-drupal_container()->get('extension_handler')->loadModule('user');
+drupal_container()->get('module_handler')->setModuleList($module_list);
+drupal_container()->get('module_handler')->load('system');
+drupal_container()->get('module_handler')->load('user');
 
 // Initialize the language system.
 drupal_language_initialize();
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index d6c963c..bee7b9d 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -5,8 +5,8 @@
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\Database\Database;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
-use Drupal\Core\ExtensionHandler;
-use Drupal\Core\ExtensionHandlerMinimal;
+use Drupal\Core\ModuleHandler;
+use Drupal\Core\InstallModuleHandler;
 use Symfony\Component\ClassLoader\UniversalClassLoader;
 use Symfony\Component\ClassLoader\ApcUniversalClassLoader;
 use Symfony\Component\DependencyInjection\Container;
@@ -891,7 +891,7 @@ function drupal_get_filename($type, $name, $filename = NULL) {
   else {
     if ($type == 'module') {
       if (empty($files[$type])) {
-        $files[$type] = drupal_container()->get('extension_handler')->getModuleList();
+        $files[$type] = drupal_container()->get('module_handler')->getModuleList();
       }
       if (isset($files[$type][$name])) {
         return $files[$type][$name];
@@ -1142,9 +1142,9 @@ function drupal_page_is_cacheable($allow_caching = NULL) {
  * @see bootstrap_hooks()
  */
 function bootstrap_invoke_all($hook) {
-  $extension_handler = drupal_container()->get('extension_handler');
-  foreach ($extension_handler->getBootstrapModules() as $module) {
-    $extension_handler->loadModule($module);
+  $module_handler = drupal_container()->get('module_handler');
+  foreach ($module_handler->getBootstrapModules() as $module) {
+    $module_handler->load($module);
     module_invoke($module, $hook);
   }
 }
@@ -1163,8 +1163,8 @@ function bootstrap_invoke_all($hook) {
  *   TRUE if the item is loaded or has already been loaded.
  */
 function drupal_load($type, $name) {
-  if ($type == 'module' && drupal_container()->get('extension_handler')->moduleExists($name)) {
-    return drupal_container()->get('extension_handler')->loadModule($name);
+  if ($type == 'module' && drupal_container()->get('module_handler')->moduleExists($name)) {
+    return drupal_container()->get('module_handler')->load($name);
   }
 
   // Once a file is included this can't be reversed during a request so do not
@@ -2437,7 +2437,7 @@ function _drupal_bootstrap_variables() {
   $conf = variable_initialize(isset($conf) ? $conf : array());
   // Load bootstrap modules.
   require_once DRUPAL_ROOT . '/core/includes/module.inc';
-  drupal_container()->get('extension_handler')->loadBootstrapModules();
+  drupal_container()->get('module_handler')->loadBootstrapModules();
 }
 
 /**
@@ -2493,40 +2493,40 @@ function drupal_container(Container $new_container = NULL) {
 /**
  * Determines which modules are implementing a hook.
  *
- * @see ExtensionHandler::moduleImplements().
+ * @see ModuleHandler::getImplementations().
  */
 function module_implements($hook) {
-  return drupal_container()->get('extension_handler')->moduleImplements($hook);
+  return drupal_container()->get('module_handler')->getImplementations($hook);
 }
 
 /**
  * Invokes a hook in all enabled modules that implement it.
  *
- * @see ExtensionHandler::moduleInvokeAll().
+ * @see ModuleHandler::invokeAll().
  */
 function module_invoke_all($hook) {
   $args = func_get_args();
   // Remove $hook from the arguments.
   unset($args[0]);
-  return drupal_container()->get('extension_handler')->moduleInvokeAll($hook, $args);
+  return drupal_container()->get('module_handler')->invokeAll($hook, $args);
 }
 
 /**
  * Passes alterable variables to specific hook_TYPE_alter() implementations.
  *
- * @see ExtensionHandler::alter().
+ * @see ModuleHandler::alter().
  */
 function drupal_alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
-  return drupal_container()->get('extension_handler')->alter($type, $data, $context1, $context2);
+  return drupal_container()->get('module_handler')->alter($type, $data, $context1, $context2);
 }
 
 /**
  * Determines whether a given module exists.
  *
- * @see ExtensionHandler::moduleExists().
+ * @see ModuleHandler::moduleExists().
  */
 function module_exists($module) {
-  return drupal_container()->get('extension_handler')->moduleExists($module);
+  return drupal_container()->get('module_handler')->moduleExists($module);
 }
 
 /**
diff --git a/core/includes/common.inc b/core/includes/common.inc
index 58f8cb4..48f1fd4 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -4774,7 +4774,7 @@ function _drupal_bootstrap_code() {
   require_once DRUPAL_ROOT . '/core/includes/entity.inc';
 
   // Load all enabled modules
-  drupal_container()->get('extension_handler')->loadAllModules();
+  drupal_container()->get('module_handler')->loadAll();
 
   // Make sure all stream wrappers are registered.
   file_get_stream_wrappers();
@@ -6373,7 +6373,7 @@ function drupal_flush_all_caches() {
 
   // Ensure that all modules that are currently supposed to be enabled are
   // actually loaded.
-  drupal_container()->get('extension_handler')->loadAllModules();
+  drupal_container()->get('module_handler')->loadAll();
 
   // Update the list of bootstrap modules.
   // Allows developers to get new hook_boot() implementations registered without
@@ -6450,7 +6450,7 @@ function debug($data, $label = NULL, $print_r = FALSE) {
  * Checks whether a version is compatible with a given dependency.
  *
  * @param $v
- *   A parsed dependency structure e.g. from ExtensionHandler::parseDependency().
+ *   A parsed dependency structure e.g. from ModuleHandler::parseDependency().
  * @param $current_version
  *   The version to check against (like 4.2).
  *
@@ -6458,7 +6458,7 @@ function debug($data, $label = NULL, $print_r = FALSE) {
  *   NULL if compatible, otherwise the original dependency version string that
  *   caused the incompatibility.
  *
- * @see ExtensionHandler::parseDependency()
+ * @see ModuleHandler::parseDependency()
  */
 function drupal_check_incompatibility($v, $current_version) {
   if (!empty($v['versions'])) {
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 279b43e..dd27421 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -332,7 +332,7 @@ function install_begin_request(&$install_state) {
       ->addArgument(new Reference('event_dispatcher'));
     // Register an extension handler for managing enabled modules.
     $container
-      ->register('extension_handler', 'Drupal\Core\ExtensionHandlerMinimal');
+      ->register('module_handler', 'Drupal\Core\InstallModuleHandler');
     drupal_container($container);
   }
 
@@ -342,8 +342,8 @@ function install_begin_request(&$install_state) {
   require_once DRUPAL_ROOT . '/core/includes/ajax.inc';
 
   // Override the module list with a minimal set of modules.
-  drupal_container()->get('extension_handler')->setModuleList(array('system' => 'core/modules/system/system.module'));
-  drupal_container()->get('extension_handler')->loadModule('system');
+  drupal_container()->get('module_handler')->setModuleList(array('system' => 'core/modules/system/system.module'));
+  drupal_container()->get('module_handler')->load('system');
 
   // Load the cache infrastructure using a "fake" cache implementation that
   // does not attempt to write to the database. We need this during the initial
@@ -1501,7 +1501,7 @@ function install_load_profile(&$install_state) {
 function install_bootstrap_full(&$install_state) {
   // Clear the statically cached extension handler. This will allow all freshly
   // installed modules to be loaded.
-  drupal_static_reset('drupal_extension_handler');
+  drupal_static_reset('drupal_module_handler');
 
   // Instantiate the kernel.
   $kernel = new DrupalKernel('prod', FALSE, drupal_classloader(), FALSE);
diff --git a/core/includes/install.inc b/core/includes/install.inc
index a87dda6..6439565 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -425,8 +425,8 @@ function drupal_install_system() {
     ->save();
 
   // Clear out module list and hook implementation statics.
-  drupal_static_reset('drupal_extension_handler');
-  drupal_container()->get('extension_handler')->setModuleList(array('system' => $system_path . '/system.module'));
+  drupal_static_reset('drupal_module_handler');
+  drupal_container()->get('module_handler')->setModuleList(array('system' => $system_path . '/system.module'));
   config_install_default_config('module', 'system');
 
   module_invoke('system', 'install');
diff --git a/core/includes/module.inc b/core/includes/module.inc
index 03680d7..df56084 100644
--- a/core/includes/module.inc
+++ b/core/includes/module.inc
@@ -283,9 +283,9 @@ function module_enable($module_list, $enable_dependencies = TRUE) {
   $schema_store = drupal_container()->get('keyvalue')->get('system.schema');
   $module_config = config('system.module');
   $disabled_config = config('system.module.disabled');
-  $extension_handler = drupal_container()->get('extension_handler');
+  $module_handler = drupal_container()->get('module_handler');
   foreach ($module_list as $module) {
-    $module_filenames = $extension_handler->getModuleList();
+    $module_filenames = $module_handler->getModuleList();
     // Only process modules that are not already enabled.
     $enabled = isset($module_filenames[$module]);
     if (!$enabled) {
@@ -311,18 +311,18 @@ function module_enable($module_list, $enable_dependencies = TRUE) {
       }
 
       // Refresh the module list in the extension handler.
-      $extension_handler->setModuleList($module_filenames);
+      $module_handler->setModuleList($module_filenames);
 
       // Load the module's code.
-      $extension_handler->loadModule($module);
+      $module_handler->load($module);
       module_load_install($module);
 
       // Refresh the module list to include it.
-      $extension_handler->moduleImplementsReset();
+      $module_handler->resetImplementations();
 
       _system_update_bootstrap_status();
 
-      // Update the kernel to include the new module
+      // Update the kernel to include the new module.
       // @todo The if statement is here because install_begin_request() creates
       //   a container without a kernel. It probably shouldn't.
       if ($kernel = drupal_container()->get('kernel', ContainerInterface::NULL_ON_INVALID_REFERENCE)) {
@@ -436,9 +436,9 @@ function module_disable($module_list, $disable_dependents = TRUE) {
 
   $module_config = config('system.module');
   $disabled_config = config('system.module.disabled');
-  $extension_handler = drupal_container()->get('extension_handler');
+  $module_handler = drupal_container()->get('module_handler');
   foreach ($module_list as $module) {
-    $enabled = $extension_handler->getModuleList();
+    $enabled = $module_handler->getModuleList();
     if (isset($enabled[$module])) {
       module_load_install($module);
       module_invoke($module, 'disable');
@@ -449,7 +449,7 @@ function module_disable($module_list, $disable_dependents = TRUE) {
         ->clear("enabled.$module")
         ->save();
       unset($enabled[$module]);
-      $extension_handler->setModuleList($enabled);
+      $module_handler->setModuleList($enabled);
       $invoke_modules[] = $module;
       watchdog('system', '%module module disabled.', array('%module' => $module), WATCHDOG_INFO);
     }
@@ -461,7 +461,7 @@ function module_disable($module_list, $disable_dependents = TRUE) {
     //   the todo in system_list_reset().
     system_list_reset();
     // Refresh the module list to exclude the disabled modules.
-    drupal_container()->get('extension_handler')->moduleImplementsReset();
+    drupal_container()->get('module_handler')->resetImplementations();
     entity_info_cache_clear();
     // Invoke hook_modules_disabled before disabling modules,
     // so we can still call module hooks to get information.
@@ -595,7 +595,7 @@ function module_hook($module, $hook) {
   }
   // If the hook implementation does not exist, check whether it may live in an
   // optional include file registered via hook_hook_info().
-  $hook_info = drupal_container()->get('extension_handler')->moduleHookInfo();
+  $hook_info = drupal_container()->get('module_handler')->getHookInfo();
   if (isset($hook_info[$hook]['group'])) {
     module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
     if (function_exists($function)) {
@@ -664,8 +664,8 @@ function drupal_required_modules() {
 function module_set_weight($module, $weight) {
   // Update the module weight in the config file that contains it.
   $module_config = config('system.module');
-  $extension_handler = drupal_container()->get('extension_handler');
-  $enabled_modules = $extension_handler->getModuleList();
+  $module_handler = drupal_container()->get('module_handler');
+  $enabled_modules = $module_handler->getModuleList();
   if ($module_config->get("enabled.$module") !== NULL) {
     $module_config
       ->set("enabled.$module", $weight)
@@ -677,7 +677,7 @@ function module_set_weight($module, $weight) {
       $sorted_with_filenames[$m] = $enabled_modules[$m];
     }
     // Refresh the module list in the extension handler.
-    $extension_handler->setModuleList($sorted_with_filenames);
+    $module_handler->setModuleList($sorted_with_filenames);
     return;
   }
   $disabled_config = config('system.module.disabled');
diff --git a/core/includes/schema.inc b/core/includes/schema.inc
index e24bb80..eb023fc 100644
--- a/core/includes/schema.inc
+++ b/core/includes/schema.inc
@@ -85,7 +85,7 @@ function drupal_get_complete_schema($rebuild = FALSE) {
         // that it contains the complete list of modules before we go on to call
         // module_load_all_includes().
         system_list_reset();
-        drupal_container()->get('extension_handler')->loadModuleIncludes('install');
+        drupal_container()->get('module_handler')->loadAllIncludes('install');
       }
 
       require_once DRUPAL_ROOT . '/core/includes/common.inc';
@@ -130,7 +130,7 @@ function drupal_get_schema_versions($module) {
   $updates = &drupal_static(__FUNCTION__, NULL);
   if (!isset($updates[$module])) {
     $updates = array();
-    foreach (drupal_container()->get('extension_handler')->getModuleList() as $loaded_module => $filename) {
+    foreach (drupal_container()->get('module_handler')->getModuleList() as $loaded_module => $filename) {
       $updates[$loaded_module] = array();
     }
 
diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 42fcd84..6378327 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -367,14 +367,14 @@ function _theme_load_registry($theme, $base_theme = NULL, $theme_engine = NULL,
       $registry = _theme_build_registry($theme, $base_theme, $theme_engine);
       // Only persist this registry if all modules are loaded. This assures a
       // complete set of theme hooks.
-      if (drupal_container()->get('extension_handler')->allModulesLoaded()) {
+      if (drupal_container()->get('module_handler')->isLoaded()) {
         _theme_save_registry($theme, $registry);
       }
     }
     return $registry;
   }
   else {
-    return new ThemeRegistry('theme_registry:runtime:' . $theme->name, 'cache', array('theme_registry' => TRUE), drupal_container()->get('extension_handler')->allModulesLoaded());
+    return new ThemeRegistry('theme_registry:runtime:' . $theme->name, 'cache', array('theme_registry' => TRUE), drupal_container()->get('module_handler')->isLoaded());
   }
 }
 
@@ -545,7 +545,7 @@ function _theme_process_registry(&$cache, $name, $type, $theme, $path) {
             // Add all modules so they can intervene with their own variable
             // processors. This allows them to provide variable processors even
             // if they are not the owner of the current hook.
-            $prefixes = array_merge($prefixes, array_keys(drupal_container()->get('extension_handler')->getModuleList()));
+            $prefixes = array_merge($prefixes, array_keys(drupal_container()->get('module_handler')->getModuleList()));
           }
           elseif ($type == 'theme_engine' || $type == 'base_theme_engine') {
             // Theme engines get an extra set that come before the normally
@@ -640,7 +640,7 @@ function _theme_build_registry($theme, $base_theme, $theme_engine) {
       _theme_process_registry($cache, $module, 'module', $module, drupal_get_path('module', $module));
     }
     // Only cache this registry if all modules are loaded.
-    if (drupal_container()->get('extension_handler')->allModulesLoaded()) {
+    if (drupal_container()->get('module_handler')->isLoaded()) {
       cache()->set("theme_registry:build:modules", $cache, CacheBackendInterface::CACHE_PERMANENT, array('theme_registry' => TRUE));
     }
   }
@@ -955,7 +955,7 @@ function theme($hook, $variables = array()) {
   // If called before all modules are loaded, we do not necessarily have a full
   // theme registry to work with, and therefore cannot process the theme
   // request properly. See also _theme_load_registry().
-  if (!drupal_container()->get('extension_handler')->allModulesLoaded() && !defined('MAINTENANCE_MODE')) {
+  if (!drupal_container()->get('module_handler')->isLoaded() && !defined('MAINTENANCE_MODE')) {
     throw new Exception(t('theme() may not be called until all modules are loaded.'));
   }
 
diff --git a/core/includes/theme.maintenance.inc b/core/includes/theme.maintenance.inc
index e1d6c70..d9999b6 100644
--- a/core/includes/theme.maintenance.inc
+++ b/core/includes/theme.maintenance.inc
@@ -56,8 +56,8 @@ function _drupal_maintenance_theme() {
   // Ensure that system.module is loaded.
   if (!function_exists('_system_rebuild_theme_data')) {
     $module_list['system']['filename'] = 'core/modules/system/system.module';
-    drupal_container()->get('extension_handler')->setModuleList($module_list);
-    drupal_container()->get('extension_handler')->loadModule('system');
+    drupal_container()->get('module_handler')->setModuleList($module_list);
+    drupal_container()->get('module_handler')->load('system');
   }
 
   $themes = list_themes();
diff --git a/core/includes/update.inc b/core/includes/update.inc
index 8405b34..fdd2e34 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -9,7 +9,7 @@
  */
 
 use Drupal\Component\Graph\Graph;
-use Drupal\Core\ExtensionHandler;
+use Drupal\Core\ModuleHandler;
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\ConfigException;
 use Drupal\Component\Uuid\Uuid;
@@ -126,10 +126,10 @@ function update_prepare_d8_bootstrap() {
 
     include_once DRUPAL_ROOT . '/core/includes/module.inc';
     include_once DRUPAL_ROOT . '/core/includes/cache.inc';
-    $extension_handler = drupal_container()->get('extension_handler');
-    $extension_handler->setModuleList(array('system' => 'core/modules/system/system.module'));
+    $module_handler = drupal_container()->get('module_handler');
+    $module_handler->setModuleList(array('system' => 'core/modules/system/system.module'));
 
-    $extension_handler->loadModule('system');
+    $module_handler->load('system');
     // Ensure the configuration directories exist and are writable, or create
     // them. If the directories have not been specified in settings.php and
     // created manually already, and either directory cannot be created by the
@@ -243,7 +243,7 @@ function update_prepare_d8_bootstrap() {
       // Populate a fixed module list (again, why did it get lost?) to avoid
       // errors due to the drupal_alter() in _system_rebuild_module_data().
       $module_list['system'] = 'core/modules/system/system.module';
-      drupal_container()->get('extension_handler')->setModuleList($module_list);
+      drupal_container()->get('module_handler')->setModuleList($module_list);
       $module_data = _system_rebuild_module_data();
 
       // Migrate each extension into configuration, varying by the extension's
@@ -274,7 +274,7 @@ function update_prepare_d8_bootstrap() {
         $sorted_with_filenames[$m] = drupal_get_filename('module', $m);
       }
 
-      drupal_container()->get('extension_handler')->setModuleList($sorted_with_filenames);
+      drupal_container()->get('module_handler')->setModuleList($sorted_with_filenames);
       $disabled_modules->save();
       $theme_config->save();
       $disabled_themes->save();
diff --git a/core/lib/Drupal/Core/CoreBundle.php b/core/lib/Drupal/Core/CoreBundle.php
index 7433de3..5498374 100644
--- a/core/lib/Drupal/Core/CoreBundle.php
+++ b/core/lib/Drupal/Core/CoreBundle.php
@@ -73,6 +73,12 @@ public function build(ContainerBuilder $container) {
       ->register('keyvalue.database', 'Drupal\Core\KeyValueStore\KeyValueDatabaseFactory')
       ->addArgument(new Reference('database'));
 
+    // Register the state k/v store as a service.
+    $container->register('state', 'Drupal\Core\KeyValueStore\KeyValueStoreInterface')
+      ->setFactoryService(new Reference('keyvalue'))
+      ->setFactoryMethod('get')
+      ->addArgument('state');
+
     $container->register('path.alias_manager', 'Drupal\Core\Path\AliasManager')
       ->addArgument(new Reference('database'))
       ->addArgument(new Reference('keyvalue'));
@@ -111,11 +117,11 @@ public function build(ContainerBuilder $container) {
       ->setFactoryMethod('get')
       ->addArgument('bootstrap');
 
-    // The ExtensionHandler manages enabled modules and provides the ability to
+    // The ModuleHandler manages enabled modules and provides the ability to
     // invoke hooks in all enabled modules.
-    $container->register('extension_handler', 'Drupal\Core\ExtensionHandler')
+    $container->register('module_handler', 'Drupal\Core\ModuleHandler')
       ->addArgument('%container.modules%')
-      ->addArgument(new Reference('keyvalue'))
+      ->addArgument(new Reference('state'))
       ->addArgument(new Reference('cache.bootstrap'));
 
     $container->register('resolver', 'Drupal\Core\ControllerResolver')
@@ -150,7 +156,7 @@ public function build(ContainerBuilder $container) {
       ->addArgument(new Reference('router.dumper'))
       ->addArgument(new Reference('lock'))
       ->addArgument(new Reference('event_dispatcher'))
-      ->addArgument(new Reference('extension_handler'));
+      ->addArgument(new Reference('module_handler'));
 
     $container->register('matcher', 'Drupal\Core\Routing\ChainMatcher');
     $container->register('legacy_url_matcher', 'Drupal\Core\LegacyUrlMatcher')
@@ -232,7 +238,7 @@ public function build(ContainerBuilder $container) {
       ->setScope('request')
       ->addTag('event_subscriber');
     $container->register('request_close_subscriber', 'Drupal\Core\EventSubscriber\RequestCloseSubscriber')
-      ->addArgument(new Reference('extension_handler'))
+      ->addArgument(new Reference('module_handler'))
       ->addTag('event_subscriber');
     $container->register('config_global_override_subscriber', 'Drupal\Core\EventSubscriber\ConfigGlobalOverrideSubscriber')
       ->addTag('event_subscriber');
diff --git a/core/lib/Drupal/Core/EventSubscriber/RequestCloseSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/RequestCloseSubscriber.php
index 04250ab..0e9ee9b 100644
--- a/core/lib/Drupal/Core/EventSubscriber/RequestCloseSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/RequestCloseSubscriber.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\Core\EventSubscriber;
 
-use Drupal\Core\ExtensionHandlerInterface;
+use Drupal\Core\ModuleHandlerInterface;
 use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\HttpKernel\Event\PostResponseEvent;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
@@ -18,15 +18,15 @@
 class RequestCloseSubscriber implements EventSubscriberInterface {
 
    /**
-   * @var ExtensionHandlerInterface
+   * @var ModuleHandlerInterface
    */
-  protected $extensionHandler;
+  protected $ModuleHandler;
 
   /**
    * Constructor.
    */
-  function __construct(ExtensionHandlerInterface $extension_handler) {
-    $this->extensionHandler = $extension_handler;
+  function __construct(ModuleHandlerInterface $module_handler) {
+    $this->ModuleHandler = $module_handler;
   }
 
   /**
@@ -48,7 +48,7 @@ public function onTerminate(PostResponseEvent $event) {
     // since these do not need to be optimized as tightly, and not doing so
     // keeps the cache entry smaller.
     if ($request_method == 'GET' || $request_method == 'HEAD') {
-      $this->extensionHandler->writeModuleImplementationsCache();
+      $this->ModuleHandler->writeImplementationsCache();
     }
     system_run_automated_cron();
   }
diff --git a/core/lib/Drupal/Core/ExtensionHandlerMinimal.php b/core/lib/Drupal/Core/InstallModuleHandler.php
similarity index 82%
rename from core/lib/Drupal/Core/ExtensionHandlerMinimal.php
rename to core/lib/Drupal/Core/InstallModuleHandler.php
index f62ae23..732f4f9 100644
--- a/core/lib/Drupal/Core/ExtensionHandlerMinimal.php
+++ b/core/lib/Drupal/Core/InstallModuleHandler.php
@@ -2,33 +2,33 @@
 
 /**
  * @file
- * Definition of Drupal\Core\ExtensionHandlerMinimal.
+ * Contains Drupal\Core\InstallModuleHandler.
  */
 
 namespace Drupal\Core;
 
-use Drupal\Core\ExtensionHandler;
+use Drupal\Core\ModuleHandler;
 use Symfony\Component\ClassLoader\UniversalClassLoader;
 
 /**
- * Class representing an ExtensionHandler that tests can use.
+ * Module handler used by the installer.
  *
- * Overrides all methods in the ExtensionHandler class that attempt to talk to
- * a database.
+ * Overrides all methods in the ModuleHandler class that attempt to talk to
+ * the state k/v store or a cache.
  */
-class ExtensionHandlerMinimal extends ExtensionHandler {
+class InstallModuleHandler extends ModuleHandler {
 
   /**
-   * Overrides Drupal\Core\ExtensionHandler::construct().
+   * Overrides Drupal\Core\ModuleHandler::construct().
    */
   public function __construct(array $module_list = array()) {
     $this->moduleList = $module_list;
   }
 
   /**
-   * Overrides Drupal\Core\ExtensionHandler::moduleImplements().
+   * Overrides Drupal\Core\ModuleHandler::getImplementations().
    */
-  public function moduleImplements($hook) {
+  public function getImplementations($hook) {
     // Fetch implementations from cache.
     if (empty($this->implementations)) {
       $this->implementations = array();
@@ -37,7 +37,7 @@ public function moduleImplements($hook) {
       // The hook is not cached, so ensure that whether or not it has
       // implementations, that the cache is updated at the end of the request.
       $this->implementations['#write_cache'] = TRUE;
-      $hook_info = $this->moduleHookInfo();
+      $hook_info = $this->getHookInfo();
       $this->implementations[$hook] = array();
       foreach ($this->moduleList as $module => $filename) {
         $include_file = isset($hook_info[$hook]['group']) && module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
@@ -78,9 +78,9 @@ public function moduleImplements($hook) {
   }
 
   /**
-   * Overrides Drupal\Core\ExtensionHandler::moduleImplementsReset().
+   * Overrides Drupal\Core\ModuleHandler::resetImplementations().
    */
-  public function moduleImplementsReset() {
+  public function resetImplementations() {
     // We maintain a persistent cache of hook implementations in addition to the
     // static cache to avoid looping through every module and every hook on each
     // request. Benchmarks show that the benefit of this caching outweighs the
@@ -97,9 +97,9 @@ public function moduleImplementsReset() {
   }
 
   /**
-   * Overrides Drupal\Core\ExtensionHandler::moduleHookInfo().
+   * Overrides Drupal\Core\ModuleHandler::getHookInfo().
    */
-  public function moduleHookInfo() {
+  public function getHookInfo() {
     // When this function is indirectly invoked from bootstrap_invoke_all() prior
     // to all modules being loaded, we do not want to cache an incomplete
     // hook_hook_info() result, so instead return an empty array. This requires
@@ -111,7 +111,7 @@ public function moduleHookInfo() {
 
     if (!isset($this->hookInfo)) {
       $this->hookInfo = array();
-      // We can't use $this->moduleInvokeAll() here or it would cause an infinite
+      // We can't use $this->invokeAll() here or it would cause an infinite
       // loop.
       foreach ($this->moduleList as $module => $filename) {
         $function = $module . '_hook_info';
@@ -134,8 +134,8 @@ public function moduleHookInfo() {
   }
 
   /**
-   * Overrides Drupal\Core\ExtensionHandler::moduleImplementsWriteCache().
+   * Overrides Drupal\Core\ModuleHandler::getImplementationsWriteCache().
    */
-  public function writeModuleImplementationsCache() {
+  public function writeImplementationsCache() {
   }
 }
diff --git a/core/lib/Drupal/Core/ExtensionHandler.php b/core/lib/Drupal/Core/ModuleHandler.php
similarity index 83%
rename from core/lib/Drupal/Core/ExtensionHandler.php
rename to core/lib/Drupal/Core/ModuleHandler.php
index 674b65d..aa83c02 100644
--- a/core/lib/Drupal/Core/ExtensionHandler.php
+++ b/core/lib/Drupal/Core/ModuleHandler.php
@@ -2,17 +2,20 @@
 
 /**
  * @file
- * Definition of Drupal\Core\ExtensionHandler.
+ * Contains Drupal\Core\ModuleHandler.
  */
 
 namespace Drupal\Core;
 
 use Drupal\Component\Graph\Graph;
 use Drupal\Core\Cache\CacheBackendInterface;
-use Drupal\Core\KeyValueStore\KeyValueFactory;
-use Drupal\Core\ExtensionHandlerInterface;
+use Drupal\Core\KeyValueStore\KeyValueStoreInterface;
+use Drupal\Core\ModuleHandlerInterface;
 
-class ExtensionHandler implements ExtensionHandlerInterface {
+/**
+ * Class that manages enabled modules in a Drupal installation.
+ */
+class ModuleHandler implements ModuleHandlerInterface {
 
   /**
    * State key/value store.
@@ -64,18 +67,18 @@ class ExtensionHandler implements ExtensionHandlerInterface {
   protected $alterFunctions;
 
   /**
-   * Constructor.
+   * Constructs a ModuleHandler object.
    */
-  public function __construct(array $module_list, KeyValueFactory $key_value, CacheBackendInterface $bootstrapCache) {
+  public function __construct(array $module_list, KeyValueStoreInterface $state, CacheBackendInterface $bootstrap_cache) {
     $this->moduleList = $module_list;
-    $this->state = $key_value->get('state');
-    $this->bootstrapCache = $bootstrapCache;
+    $this->state = $state;
+    $this->bootstrapCache = $bootstrap_cache;
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::loadModule().
+   * Implements \Drupal\Core\ModuleHandlerInterface::load().
    */
-  public function loadModule($name) {
+  public function load($name) {
     if (isset($this->loadedFiles[$name])) {
       return TRUE;
     }
@@ -90,59 +93,59 @@ public function loadModule($name) {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::loadAllModules().
+   * Implements \Drupal\Core\ModuleHandlerInterface::loadAll().
    */
-  public function loadAllModules() {
+  public function loadAll() {
     if (!$this->loaded) {
       foreach ($this->moduleList as $module => $filename) {
-        $this->loadModule($module);
+        $this->load($module);
       }
       $this->loaded = TRUE;
     }
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::reloadModules().
+   * Implements \Drupal\Core\ModuleHandlerInterface::reload().
    */
-  public function reloadModules() {
+  public function reload() {
     $this->loaded = FALSE;
-    $this->loadAllModules();
+    $this->loadAll();
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::loadBootstrapModules().
+   * Implements \Drupal\Core\ModuleHandlerInterface::loadBootstrapModules().
    */
   public function loadBootstrapModules() {
     if (!$this->loaded) {
       foreach ($this->getBootstrapModules() as $module) {
-        $this->loadModule($module);
+        $this->load($module);
       }
     }
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::allModulesLoaded().
+   * Implements \Drupal\Core\ModuleHandlerInterface::isLoaded().
    */
-  public function allModulesLoaded() {
+  public function isLoaded() {
     return $this->loaded;
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::getModuelList().
+   * Implements \Drupal\Core\ModuleHandlerInterface::getModuelList().
    */
   public function getModuleList() {
     return $this->moduleList;
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::setModuleList().
+   * Implements \Drupal\Core\ModuleHandlerInterface::setModuleList().
    */
   public function setModuleList(array $module_list = array()) {
     $this->moduleList = $module_list;
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::getBootstrapModules().
+   * Implements \Drupal\Core\ModuleHandlerInterface::getBootstrapModules().
    */
   public function getBootstrapModules() {
     if (isset($this->bootstrapModules)) {
@@ -161,7 +164,7 @@ public function getBootstrapModules() {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::buildModuleDependencies().
+   * Implements \Drupal\Core\ModuleHandlerInterface::buildModuleDependencies().
    */
   public function buildModuleDependencies($files) {
     foreach ($files as $filename => $file) {
@@ -184,26 +187,25 @@ public function buildModuleDependencies($files) {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::moduleExists().
+   * Implements \Drupal\Core\ModuleHandlerInterface::moduleExists().
    */
   public function moduleExists($module) {
     return isset($this->moduleList[$module]);
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::loadModuleIncludes().
+   * Implements \Drupal\Core\ModuleHandlerInterface::loadAllIncludes().
    */
-  public function loadModuleIncludes($type, $name = NULL) {
+  public function loadAllIncludes($type, $name = NULL) {
     foreach ($this->moduleList as $module => $filename) {
       module_load_include($type, $module, $name);
     }
   }
 
-
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::moduleImplements().
+   * Implements \Drupal\Core\ModuleHandlerInterface::getImplementations().
    */
-  public function moduleImplements($hook) {
+  public function getImplementations($hook) {
     // Fetch implementations from cache.
     if (empty($this->implementations)) {
       $implementations = $this->bootstrapCache->get('module_implements');
@@ -219,7 +221,7 @@ public function moduleImplements($hook) {
       // The hook is not cached, so ensure that whether or not it has
       // implementations, that the cache is updated at the end of the request.
       $this->implementations['#write_cache'] = TRUE;
-      $hook_info = $this->moduleHookInfo();
+      $hook_info = $this->getHookInfo();
       $this->implementations[$hook] = array();
       foreach ($this->moduleList as $module => $filename) {
         $include_file = isset($hook_info[$hook]['group']) && module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
@@ -259,19 +261,9 @@ public function moduleImplements($hook) {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::getModuleHookImplementations().
-   */
-  public function getModuleHookImplementations() {
-    if (empty($this->implementations)) {
-      return array();
-    }
-    return $this->implementations;
-  }
-
-  /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::moduleImplementsReset().
+   * Implements \Drupal\Core\ModuleHandlerInterface::resetImplementations().
    */
-  public function moduleImplementsReset() {
+  public function resetImplementations() {
     // We maintain a persistent cache of hook implementations in addition to the
     // static cache to avoid looping through every module and every hook on each
     // request. Benchmarks show that the benefit of this caching outweighs the
@@ -290,9 +282,9 @@ public function moduleImplementsReset() {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::moduleHookInfo().
+   * Implements \Drupal\Core\ModuleHandlerInterface::getHookInfo().
    */
-  public function moduleHookInfo() {
+  public function getHookInfo() {
     // When this function is indirectly invoked from bootstrap_invoke_all() prior
     // to all modules being loaded, we do not want to cache an incomplete
     // hook_hookInfo() result, so instead return an empty array. This requires
@@ -306,7 +298,7 @@ public function moduleHookInfo() {
       $cache = $this->bootstrapCache->get('hook_info');
       if ($cache === FALSE) {
         // Rebuild the cache and save it.
-        // We can't use $this->moduleInvokeAll() here or it would cause an infinite
+        // We can't use $this->invokeAll() here or it would cause an infinite
         // loop.
         foreach ($this->moduleList as $module => $filename) {
           $function = $module . '_hook_info';
@@ -336,9 +328,9 @@ public function moduleHookInfo() {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::moduleImplementsWriteCache().
+   * Implements \Drupal\Core\ModuleHandlerInterface::getImplementationsWriteCache().
    */
-  public function writeModuleImplementationsCache() {
+  public function writeImplementationsCache() {
     if (isset($this->implementations['#write_cache'])) {
       unset($this->implementations['#write_cache']);
       $this->bootstrapCache->set('module_implements', $this->implementations);
@@ -346,11 +338,11 @@ public function writeModuleImplementationsCache() {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::moduleInvokeAll().
+   * Implements \Drupal\Core\ModuleHandlerInterface::invokeAll().
    */
-  public function moduleInvokeAll($hook, $args) {
+  public function invokeAll($hook, $args) {
     $return = array();
-    foreach ($this->moduleImplements($hook) as $module) {
+    foreach ($this->getImplementations($hook) as $module) {
       $function = $module . '_' . $hook;
       if (function_exists($function)) {
         $result = call_user_func_array($function, $args);
@@ -367,7 +359,7 @@ public function moduleInvokeAll($hook, $args) {
   }
 
   /**
-   * Implements Drupal\Core\ExtensionHandlerInterface::alter().
+   * Implements \Drupal\Core\ModuleHandlerInterface::alter().
    */
   public function alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
     // Most of the time, $type is passed as a string, so for performance,
@@ -395,10 +387,10 @@ public function alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
     if (!isset($this->alterFunctions[$cid])) {
       $this->alterFunctions[$cid] = array();
       $hook = $type . '_alter';
-      $modules = $this->moduleImplements($hook);
+      $modules = $this->getImplementations($hook);
       if (!isset($extra_types)) {
         // For the more common case of a single hook, we do not need to call
-        // function_exists(), since $this->moduleImplements() returns only modules with
+        // function_exists(), since $this->getImplementations() returns only modules with
         // implementations.
         foreach ($modules as $module) {
           $this->alterFunctions[$cid][] = $module . '_' . $hook;
@@ -409,19 +401,19 @@ public function alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
         // implements at least one of them.
         $extra_modules = array();
         foreach ($extra_types as $extra_type) {
-          $extra_modules = array_merge($extra_modules, $this->moduleImplements($extra_type . '_alter'));
+          $extra_modules = array_merge($extra_modules, $this->getImplementations($extra_type . '_alter'));
         }
         // If any modules implement one of the extra hooks that do not implement
         // the primary hook, we need to add them to the $modules array in their
-        // appropriate order. $this->moduleImplements() can only return ordered
+        // appropriate order. $this->getImplementations() can only return ordered
         // implementations of a single hook. To get the ordered implementations
-        // of multiple hooks, we mimic the $this->moduleImplements() logic of first
+        // of multiple hooks, we mimic the $this->getImplementations() logic of first
         // ordering by $this->getModuleList(), and then calling
         // $this->alter('module_implements').
         if (array_diff($extra_modules, $modules)) {
           // Merge the arrays and order by getModuleList().
           $modules = array_intersect(array_keys($this->moduleList), array_merge($modules, $extra_modules));
-          // Since $this->moduleImplements() already took care of loading the necessary
+          // Since $this->getImplementations() already took care of loading the necessary
           // include files, we can safely pass FALSE for the array values.
           $implementations = array_fill_keys($modules, FALSE);
           // Let modules adjust the order solely based on the primary hook. This
diff --git a/core/lib/Drupal/Core/ExtensionHandlerInterface.php b/core/lib/Drupal/Core/ModuleHandlerInterface.php
similarity index 87%
rename from core/lib/Drupal/Core/ExtensionHandlerInterface.php
rename to core/lib/Drupal/Core/ModuleHandlerInterface.php
index 1ff835b..6f49f35 100644
--- a/core/lib/Drupal/Core/ExtensionHandlerInterface.php
+++ b/core/lib/Drupal/Core/ModuleHandlerInterface.php
@@ -2,12 +2,19 @@
 
 /**
  * @file
- * Contains Drupal\Core\ExtensionHandlerInterface.
+ * Contains Drupal\Core\ModuleHandlerInterface.
  */
 
 namespace Drupal\Core;
 
-interface ExtensionHandlerInterface {
+/**
+ * Interface for classes that manage a set of enabled modules.
+ *
+ * Classes implementing this interface work with a fixed list of modules and are
+ * responsible for loading module files and maintaining information about module
+ * dependencies and hook implementations.
+ */
+interface ModuleHandlerInterface {
 
   /**
    * Includes a file with the provided type and name.
@@ -20,12 +27,12 @@
    * @return
    *   TRUE if the item is loaded or has already been loaded.
    */
-  public function loadModule($name);
+  public function load($name);
 
   /**
    * Loads all the modules that have been enabled.
    */
-  public function loadAllModules();
+  public function loadAll();
 
   /**
    * Loads all bootstrap modules.
@@ -39,12 +46,12 @@ public function loadBootstrapModules();
    *   A Boolean indicating whether all modules have been loaded. This means all
    *   modules; the load status of bootstrap modules cannot be checked.
    */
-  public function allModulesLoaded();
+  public function isLoaded();
 
   /**
    * Reloads all enabled modules.
    */
-  public function reloadModules();
+  public function reload();
 
   /**
    * Returns a list of currently active modules.
@@ -89,7 +96,7 @@ public function moduleExists($module);
   /**
    * Loads an include file for each module enabled.
    */
-  public function loadModuleIncludes($type, $name = NULL);
+  public function loadAllIncludes($type, $name = NULL);
 
   /**
    * Determines which modules are implementing a hook.
@@ -100,19 +107,13 @@ public function loadModuleIncludes($type, $name = NULL);
    * @return
    *   An array with the names of the modules which are implementing this hook.
    *
-   * @see module_implements_write_cache()
    */
-  public function moduleImplements($hook);
+  public function getImplementations($hook);
 
   /**
    * Regenerates the stored list of hook implementations.
    */
-  public function moduleImplementsReset();
-
-  /**
-   * Returns the hook implementation cache.
-   */
-  public function getModuleHookImplementations();
+  public function resetImplementations();
 
   /**
    * Retrieves a list of hooks that are declared through hook_hook_info().
@@ -124,14 +125,14 @@ public function getModuleHookImplementations();
    *
    * @see hook_hook_info()
    */
-  public function moduleHookInfo();
+  public function getHookInfo();
 
   /**
    * Writes the hook implementation cache.
    *
-   * @see $this->moduleImplements()
+   * @see $this->getImplementations()
    */
-  public function writeModuleImplementationsCache();
+  public function writeImplementationsCache();
 
   /**
    * Invokes a hook in all enabled modules that implement it.
@@ -145,7 +146,7 @@ public function writeModuleImplementationsCache();
    *   An array of return values of the hook implementations. If modules return
    *   arrays from their implementations, those are merged into one array.
    */
-  public function moduleInvokeAll($hook, $args);
+  public function invokeAll($hook, $args);
 
   /**
    * Passes alterable variables to specific hook_TYPE_alter() implementations.
diff --git a/core/lib/Drupal/Core/Routing/RouteBuilder.php b/core/lib/Drupal/Core/Routing/RouteBuilder.php
index e74c4c6..f6ec656 100644
--- a/core/lib/Drupal/Core/Routing/RouteBuilder.php
+++ b/core/lib/Drupal/Core/Routing/RouteBuilder.php
@@ -13,7 +13,7 @@
 use Symfony\Component\Routing\RouteCollection;
 use Symfony\Component\Routing\Route;
 
-use Drupal\Core\ExtensionHandlerInterface;
+use Drupal\Core\ModuleHandlerInterface;
 use Drupal\Core\Lock\LockBackendInterface;
 
 /**
@@ -48,9 +48,9 @@ class RouteBuilder {
   /**
    * The extension handler for retieving the list of enabled modules.
    *
-   * @var \Drupal\Core\ExtensionHandlerInterface
+   * @var \Drupal\Core\ModuleHandlerInterface
    */
-  protected $extensionHandler;
+  protected $ModuleHandler;
 
   /**
    * Construcs the RouteBuilder using the passed MatcherDumperInterface.
@@ -62,11 +62,11 @@ class RouteBuilder {
    * @param \Symfony\Component\EventDispatcherEventDispatcherInterface
    *   The event dispatcher to notify of routes.
    */
-  public function __construct(MatcherDumperInterface $dumper, LockBackendInterface $lock, EventDispatcherInterface $dispatcher, ExtensionHandlerInterface $extension_handler) {
+  public function __construct(MatcherDumperInterface $dumper, LockBackendInterface $lock, EventDispatcherInterface $dispatcher, ModuleHandlerInterface $module_handler) {
     $this->dumper = $dumper;
     $this->lock = $lock;
     $this->dispatcher = $dispatcher;
-    $this->extensionHandler = $extension_handler;
+    $this->ModuleHandler = $module_handler;
   }
 
   /**
@@ -85,7 +85,7 @@ public function rebuild() {
 
     // We need to manually call each module so that we can know which module
     // a given item came from.
-    foreach ($this->extensionHandler->getModuleList() as $module => $filename) {
+    foreach ($this->ModuleHandler->getModuleList() as $module => $filename) {
       $collection = new RouteCollection();
       $routing_file = DRUPAL_ROOT . '/' . dirname($filename) . '/' . $module . '.routing.yml';
       if (file_exists($routing_file)) {
diff --git a/core/modules/breakpoint/breakpoint.install b/core/modules/breakpoint/breakpoint.install
index 9fd1054..cba7b1b 100644
--- a/core/modules/breakpoint/breakpoint.install
+++ b/core/modules/breakpoint/breakpoint.install
@@ -18,5 +18,5 @@ function breakpoint_enable() {
   _breakpoint_theme_enabled(array_keys($themes));
 
   // Import breakpoints from modules.
-  _breakpoint_modules_enabled(array_keys(drupal_container()->get('extension_handler')->getModuleList()));
+  _breakpoint_modules_enabled(array_keys(drupal_container()->get('module_handler')->getModuleList()));
 }
diff --git a/core/modules/field/field.module b/core/modules/field/field.module
index 7d16a84..662c866 100644
--- a/core/modules/field/field.module
+++ b/core/modules/field/field.module
@@ -504,7 +504,7 @@ function field_modules_disabled($modules) {
 function field_sync_field_status() {
   // Refresh the 'active' and 'storage_active' columns according to the current
   // set of enabled modules.
-  $modules = array_keys(drupal_container()->get('extension_handler')->getModuleList());
+  $modules = array_keys(drupal_container()->get('module_handler')->getModuleList());
   foreach ($modules as $module_name) {
     field_associate_fields($module_name);
   }
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php
index 795d4d5..38096db 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php
@@ -139,7 +139,7 @@ protected function languageNegotiationUpdate($op = 'enable') {
       $function = "module_{$op}";
       $function($modules);
       // Reset hook implementation cache.
-      drupal_container()->get('extension_handler')->moduleImplementsReset();
+      drupal_container()->get('module_handler')->resetImplementations();
     }
 
     drupal_static_reset('language_types_info');
diff --git a/core/modules/layout/lib/Drupal/layout/Plugin/Derivative/Layout.php b/core/modules/layout/lib/Drupal/layout/Plugin/Derivative/Layout.php
index c5de29e..1efbc10 100644
--- a/core/modules/layout/lib/Drupal/layout/Plugin/Derivative/Layout.php
+++ b/core/modules/layout/lib/Drupal/layout/Plugin/Derivative/Layout.php
@@ -10,7 +10,7 @@
 use DirectoryIterator;
 use Drupal\Component\Plugin\Derivative\DerivativeInterface;
 use Drupal\Core\Config\FileStorage;
-use Drupal\Core\ExtensionHandlerInterface;
+use Drupal\Core\ModuleHandlerInterface;
 
 /**
  * Layout plugin derivative definition.
@@ -61,7 +61,7 @@ public function getDerivativeDefinitions(array $base_plugin_definition) {
     // Add all modules as possible layout providers.
     // @todo Change this class so that it gets the extension handler injected
     //   into it.
-    foreach (drupal_container()->get('extension_handler')->getModuleList() as $module => $filename) {
+    foreach (drupal_container()->get('module_handler')->getModuleList() as $module => $filename) {
       $available_layout_providers[$module] = array(
         'type' => 'module',
         'provider' => $module,
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
index 96856ec..222e6a2 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
@@ -213,17 +213,17 @@ protected function installSchema($module, $table) {
    */
   protected function enableModules(array $modules, $install = TRUE) {
     // Explicitly set the list of modules in the extension handler.
-    $enabled = $this->container->get('extension_handler')->getModuleList();
+    $enabled = $this->container->get('module_handler')->getModuleList();
     foreach ($modules as $module) {
       $enabled[$module] = drupal_get_filename('module', $module);
       // Call module_enable() to enable (install) the new module.
       if ($install) {
         module_enable(array($module), FALSE);
       }
-      $this->container->get('extension_handler')->setModuleList($enabled);
+      $this->container->get('module_handler')->setModuleList($enabled);
     }
-    $this->container->get('extension_handler')->moduleImplementsReset();
-    $this->container->get('extension_handler')->reloadModules();
+    $this->container->get('module_handler')->resetImplementations();
+    $this->container->get('module_handler')->reload();
   }
 
 }
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php
index fe25549..75c016e 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/DrupalUnitTestBaseTest.php
@@ -39,7 +39,7 @@ function testSetUp() {
     // Verify that specified $modules have been loaded.
     $this->assertTrue(function_exists('entity_test_permission'), "$module.module was loaded.");
     // Verify that there is a fixed module list.
-    $this->assertIdentical(array_keys(drupal_container()->get('extension_handler')->getModuleList()), array($module));
+    $this->assertIdentical(array_keys(drupal_container()->get('module_handler')->getModuleList()), array($module));
     $this->assertIdentical(module_implements('permission'), array($module));
 
     // Verify that no modules have been installed.
@@ -54,7 +54,7 @@ function testEnableModulesLoad() {
 
     // Verify that the module does not exist yet.
     $this->assertFalse(module_exists($module), "$module module not found.");
-    $list = array_keys(drupal_container()->get('extension_handler')->getModuleList());
+    $list = array_keys(drupal_container()->get('module_handler')->getModuleList());
     $this->assertFalse(in_array($module, $list), "$module module not found in the extension handler's module list.");
     $list = module_implements('permission');
     $this->assertFalse(in_array($module, $list), "{$module}_permission() in module_implements() not found.");
@@ -64,7 +64,7 @@ function testEnableModulesLoad() {
 
     // Verify that the module exists.
     $this->assertTrue(module_exists($module), "$module module found.");
-    $list = array_keys(drupal_container()->get('extension_handler')->getModuleList());
+    $list = array_keys(drupal_container()->get('module_handler')->getModuleList());
     $this->assertTrue(in_array($module, $list), "$module module found in the extension handler's module list.");
     $list = module_implements('permission');
     $this->assertTrue(in_array($module, $list), "{$module}_permission() in module_implements() found.");
@@ -83,7 +83,7 @@ function testEnableModulesInstall() {
 
     // Verify that the module does not exist yet.
     $this->assertFalse(module_exists($module), "$module module not found.");
-    $list = array_keys(drupal_container()->get('extension_handler')->getModuleList());
+    $list = array_keys(drupal_container()->get('module_handler')->getModuleList());
     $this->assertFalse(in_array($module, $list), "$module module not found in the extension handler's module list.");
     $list = module_implements('permission');
     $this->assertFalse(in_array($module, $list), "{$module}_permission() in module_implements() not found.");
@@ -97,7 +97,7 @@ function testEnableModulesInstall() {
 
     // Verify that the enabled module exists.
     $this->assertTrue(module_exists($module), "$module module found.");
-    $list = array_keys(drupal_container()->get('extension_handler')->getModuleList());
+    $list = array_keys(drupal_container()->get('module_handler')->getModuleList());
     $this->assertTrue(in_array($module, $list), "$module module found in the extension handler's module list.");
     $list = module_implements('permission');
     $this->assertTrue(in_array($module, $list), "{$module}_permission() in module_implements() found.");
diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/EnableDisableTest.php b/core/modules/system/lib/Drupal/system/Tests/Module/EnableDisableTest.php
index ae829db..4a32d97 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/EnableDisableTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/EnableDisableTest.php
@@ -43,7 +43,7 @@ function testEnableDisable() {
 
     // Remove already enabled modules (via installation profile).
     // @todo Remove this after removing all dependencies from Testing profile.
-    foreach ($this->container->get('extension_handler')->getModuleList() as $dependency => $filename) {
+    foreach ($this->container->get('module_handler')->getModuleList() as $dependency => $filename) {
       // Exclude required modules. Only installation profile "suggestions" can
       // be disabled and uninstalled.
       if (isset($modules[$dependency])) {
diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleApiTest.php b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleApiTest.php
index 8787f9b..5ea5306 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleApiTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleApiTest.php
@@ -61,7 +61,7 @@ function testModuleList() {
       'system' => 'core/modules/system/system.module',
       'menu' => 'core/modules/menu/menu.module',
     );
-    $this->container->get('extension_handler')->setModuleList($fixed_list);
+    $this->container->get('module_handler')->setModuleList($fixed_list);
     $new_module_list = array_combine(array_keys($fixed_list), array_keys($fixed_list));
     $this->assertModuleList($new_module_list, t('When using a fixed list'));
 
@@ -75,7 +75,7 @@ function testModuleList() {
    */
   protected function assertModuleList(Array $expected_values, $condition) {
     $expected_values = array_values(array_unique($expected_values));
-    $enabled_modules = array_keys($this->container->get('extension_handler')->getModuleList());
+    $enabled_modules = array_keys($this->container->get('module_handler')->getModuleList());
     $enabled_modules = sort($enabled_modules);
     $this->assertEqual($expected_values, $enabled_modules, format_string('@condition: extension handler returns correct results', array('@condition' => $condition)));
   }
@@ -83,7 +83,7 @@ protected function assertModuleList(Array $expected_values, $condition) {
   /**
    * Test module_implements() caching.
    */
-  function testModuleImplements() {
+  function testgetImplementations() {
     // Clear the cache.
     cache('bootstrap')->delete('module_implements');
     $this->assertFalse(cache('bootstrap')->get('module_implements'), 'The module implements cache is empty.');
@@ -101,13 +101,11 @@ function testModuleImplements() {
     // already loaded when the cache is rebuilt.
     // For that activate the module_test which provides the file to load.
     module_enable(array('module_test'));
-    $extension_handler = drupal_container()->get('extension_handler');
-    $extension_handler->loadAllModules();
+    $module_handler = drupal_container()->get('module_handler');
+    $module_handler->loadAll();
     module_load_include('inc', 'module_test', 'module_test.file');
-    $modules = $extension_handler->moduleImplements('test_hook');
+    $modules = $module_handler->getImplementations('test_hook');
     $this->assertTrue(in_array('module_test', $modules), 'Hook found.');
-    $module_implementations = $extension_handler->getModuleHookImplementations();
-    $this->assertEqual($module_implementations['test_hook']['module_test'], 'file', 'Include file detected.');
   }
 
   /**
@@ -123,7 +121,7 @@ function testModuleInvoke() {
   /**
    * Test that module_invoke_all() can load a hook defined in hook_hook_info().
    */
-  function testModuleInvokeAll() {
+  function testinvokeAll() {
     module_enable(array('module_test'), FALSE);
     $this->resetAll();
     $this->drupalGet('module-test/hook-dynamic-loading-invoke-all');
@@ -133,10 +131,10 @@ function testModuleInvokeAll() {
   /**
    * Test that a menu item load function can invoke hooks defined in hook_hook_info().
    *
-   * We test this separately from testModuleInvokeAll(), because menu item load
+   * We test this separately from testinvokeAll(), because menu item load
    * functions execute early in the request handling.
    */
-  function testModuleInvokeAllDuringLoadFunction() {
+  function testinvokeAllDuringLoadFunction() {
     module_enable(array('module_test'), FALSE);
     $this->resetAll();
     $this->drupalGet('module-test/hook-dynamic-loading-invoke-all-during-load/module_test');
diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
index 49a29cf..a45a616 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
@@ -151,7 +151,7 @@ function assertModules(array $modules, $enabled) {
       else {
         $message = 'Module "@module" is not enabled.';
       }
-      $this->assertEqual($this->container->get('extension_handler')->moduleExists($module), $enabled, format_string($message, array('@module' => $module)));
+      $this->assertEqual($this->container->get('module_handler')->moduleExists($module), $enabled, format_string($message, array('@module' => $module)));
     }
   }
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/Theme/RegistryTest.php b/core/modules/system/lib/Drupal/system/Tests/Theme/RegistryTest.php
index 1b683bb..5ab43ca 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Theme/RegistryTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/RegistryTest.php
@@ -40,7 +40,7 @@ function testRaceCondition() {
 
     // Directly instantiate the theme registry, this will cause a base cache
     // entry to be written in __construct().
-    $registry = new ThemeRegistry($cid, 'cache', array('theme_registry' => TRUE), $this->container->get('extension_handler')->allModulesLoaded());
+    $registry = new ThemeRegistry($cid, 'cache', array('theme_registry' => TRUE), $this->container->get('module_handler')->isLoaded());
 
     $this->assertTrue(cache()->get($cid), 'Cache entry was created.');
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
index 1430f4d..6e9b383 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
@@ -179,7 +179,7 @@ function testRegistryRebuild() {
     // container and ensure the extension handler is loaded, otherwise theme()
     // throws an exception.
     $this->rebuildContainer();
-    $this->container->get('extension_handler')->loadAllModules();
+    $this->container->get('module_handler')->loadAll();
     $this->assertIdentical(theme('theme_test_foo', array('foo' => 'b')), '', 'The theme registry does not contain theme_test_foo, because the module is disabled.');
 
     module_enable(array('theme_test'), FALSE);
@@ -187,7 +187,7 @@ function testRegistryRebuild() {
     // container and ensure the extension handler is loaded, otherwise theme()
     // throws an exception.
     $this->rebuildContainer();
-    $this->container->get('extension_handler')->loadAllModules();
+    $this->container->get('module_handler')->loadAll();
     $this->assertIdentical(theme('theme_test_foo', array('foo' => 'c')), 'c', 'The theme registry contains theme_test_foo again after re-enabling the module.');
   }
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/BareMinimalUpgradePathTest.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/BareMinimalUpgradePathTest.php
index 2be9d12..499acf2 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/BareMinimalUpgradePathTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/BareMinimalUpgradePathTest.php
@@ -82,7 +82,7 @@ public function testBasicMinimalUpgrade() {
     $this->assertFalse($result, 'No {menu_links} entry exists for user/autocomplete');
 
     // Verify that all required modules are enabled.
-    $enabled = $this->container->get('extension_handler')->getModuleList();
+    $enabled = $this->container->get('module_handler')->getModuleList();
     $required = array_filter(system_rebuild_module_data(), function ($data) {
       return !empty($data->info['required']);
     });
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php
index 7034c01..2e3c725 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php
@@ -37,7 +37,7 @@ public function testDisabledUpgrade() {
     $this->assertTrue($this->performUpgrade(), 'The upgrade was completed successfully.');
 
     // Get enabled modules.
-    $enabled = drupal_container()->get('extension_handler')->getModuleList();
+    $enabled = drupal_container()->get('module_handler')->getModuleList();
     // Get all available modules.
     $available = system_rebuild_module_data();
     // Filter out hidden test modules.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
index 09f2b50..41432c6 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
@@ -265,8 +265,8 @@ protected function performUpgrade($register_errors = TRUE) {
 
     // Reload module list for modules that are enabled in the test database
     // but not on the test client.
-    drupal_container()->get('extension_handler')->moduleImplementsReset();
-    drupal_container()->get('extension_handler')->reloadModules();
+    drupal_container()->get('module_handler')->resetImplementations();
+    drupal_container()->get('module_handler')->reload();
 
     // Rebuild the container and all caches.
     $this->rebuildContainer();
diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 21b1366..37a2bf2 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -1204,7 +1204,7 @@ function system_modules_submit($form, &$form_state) {
 
   // Gets list of modules prior to install process, unsets $form_state['storage']
   // so we don't get redirected back to the confirmation form.
-  $pre_install_list = drupal_container()->get('extension_handler')->getModuleList();
+  $pre_install_list = drupal_container()->get('module_handler')->getModuleList();
   unset($form_state['storage']);
 
   // Reverse the 'enable' list, to order dependencies before dependents.
@@ -1216,7 +1216,7 @@ function system_modules_submit($form, &$form_state) {
 
   // Gets module list after install process, flushes caches and displays a
   // message if there are changes.
-  $post_install_list = drupal_container()->get('extension_handler')->getModuleList();
+  $post_install_list = drupal_container()->get('module_handler')->getModuleList();
   if ($pre_install_list != $post_install_list) {
     drupal_flush_all_caches();
     drupal_set_message(t('The configuration options have been saved.'));
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 01baa71..e3f1539 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -400,7 +400,7 @@ function system_requirements($phase) {
     );
 
     // Check installed modules.
-    foreach (drupal_container()->get('extension_handler')->getModuleList() as $module => $filename) {
+    foreach (drupal_container()->get('module_handler')->getModuleList() as $module => $filename) {
       $updates = drupal_get_schema_versions($module);
       if ($updates !== FALSE) {
         $default = drupal_get_installed_schema_version($module);
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 1e4573d..fd1b606 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -2752,7 +2752,7 @@ function system_get_info($type, $name = NULL) {
   $info = array();
   if ($type == 'module') {
     $data = system_rebuild_module_data();
-    foreach (drupal_container()->get('extension_handler')->getModuleList() as $module => $filename) {
+    foreach (drupal_container()->get('module_handler')->getModuleList() as $module => $filename) {
       $info[$module] = $data[$module]->info;
     }
   }
@@ -2895,7 +2895,7 @@ function system_rebuild_module_data() {
       $record->schema_version = SCHEMA_UNINSTALLED;
       $files[$module] = $record->filename;
     }
-    $modules = drupal_container()->get('extension_handler')->buildModuleDependencies($modules);
+    $modules = drupal_container()->get('module_handler')->buildModuleDependencies($modules);
     $modules_cache = $modules;
 
     // Store filenames to allow system_list() and drupal_get_filename() to
diff --git a/core/modules/update/lib/Drupal/update/Tests/UpdateUploadTest.php b/core/modules/update/lib/Drupal/update/Tests/UpdateUploadTest.php
index d3bcdb8..f785151 100644
--- a/core/modules/update/lib/Drupal/update/Tests/UpdateUploadTest.php
+++ b/core/modules/update/lib/Drupal/update/Tests/UpdateUploadTest.php
@@ -36,7 +36,7 @@ public function setUp() {
   /**
    * Tests upload and extraction of a module.
    */
-  public function testUploadModule() {
+  public function testUpload() {
     // Images are not valid archives, so get one and try to install it. We
     // need an extra variable to store the result of drupalGetTestFiles()
     // since reset() takes an argument by reference and passing in a constant
diff --git a/core/scripts/dump-database-d6.sh b/core/scripts/dump-database-d6.sh
index 18453e6..106568d 100644
--- a/core/scripts/dump-database-d6.sh
+++ b/core/scripts/dump-database-d6.sh
@@ -44,7 +44,7 @@
 
 ENDOFHEADER;
 
-foreach (drupal_container()->get('extension_handler')->getModuleList() as $module => $filename) {
+foreach (drupal_container()->get('module_handler')->getModuleList() as $module => $filename) {
   $output .= " *  - $module\n";
 }
 $output .= " */\n\n";
diff --git a/core/scripts/dump-database-d7.sh b/core/scripts/dump-database-d7.sh
index 8489520..3b8597d 100644
--- a/core/scripts/dump-database-d7.sh
+++ b/core/scripts/dump-database-d7.sh
@@ -45,7 +45,7 @@
 
 ENDOFHEADER;
 
-foreach (drupal_container()->get('extension_handler')->getModuleList() as $module => $filename) {
+foreach (drupal_container()->get('module_handler')->getModuleList() as $module => $filename) {
   $output .= " *  - $module\n";
 }
 $output .= " */\n\n";
diff --git a/core/update.php b/core/update.php
index 0b5570c..69f058a 100644
--- a/core/update.php
+++ b/core/update.php
@@ -436,13 +436,13 @@ function update_check_requirements($skip_warnings = FALSE) {
   // Load module basics.
   include_once DRUPAL_ROOT . '/core/includes/module.inc';
   $module_list['system'] = 'core/modules/system/system.module';
-  $extension_handler = drupal_container()->get('extension_handler');
-  $extension_handler->setModuleList($module_list);
-  $extension_handler->loadModule('system');
+  $module_handler = drupal_container()->get('module_handler');
+  $module_handler->setModuleList($module_list);
+  $module_handler->load('system');
 
   // Reset the module implementations cache so that any new hook implementations
   // in updated code are picked up.
-  $extension_handler->moduleImplementsReset();
+  $module_handler->resetImplementations();
 
   // Set up $language, since the installer components require it.
   drupal_language_initialize();