core/modules/contextual/contextual.module

@@ -6,6 +6,21 @@
  * Adds contextual links to perform actions related to elements on a page.
  */
 
+/**
+ * Implements hook_menu().
+ */
+function contextual_menu() {
+  // @todo Remove this menu item in http://drupal.org/node/1954892 when theme
+  //   callbacks are replaced with something else.
+  $items['contextual/render'] = array(
+    'route_name' => 'contextual.render',
+    'theme callback' => 'ajax_base_page_theme',
+    'type' => MENU_CALLBACK,
+  );
+
+  return $items;
+}
+
 /**
  * Implements hook_toolbar().
  */

core/modules/contextual/contextual.routing.yml

@@ -2,7 +2,5 @@ contextual.render:
   path: '/contextual/render'
   defaults:
     _controller: '\Drupal\contextual\ContextualController::render'
-  options:
-    _theme: ajax_base_page
   requirements:
     _permission: 'access contextual links'

core/modules/contextual/css/contextual.theme.css

@@ -91,9 +91,7 @@
 }
 .contextual-region .contextual .contextual-links a {
   background-color: #fff;
-  /* This is an unfortunately necessary use of !important to prevent white
-   * links on a white background or some similar illegible combination. */
-  color: #333 !important;
+  color: #333;
   display: block;
   font-family: sans-serif;
   font-size: small;

core/modules/edit/edit.module

@@ -17,6 +17,26 @@
 use Drupal\entity\Entity\EntityDisplay;
 use Drupal\user\TempStoreFactory;
 
+/**
+ * Implements hook_menu().
+ */
+function edit_menu() {
+  // @todo Remove these menu items in http://drupal.org/node/1954892 when theme
+  //   callbacks are replaced with something else.
+  $items['edit/metadata'] = array(
+    'route_name' => 'edit.metadata',
+    'theme callback' => 'ajax_base_page_theme',
+    'type' => MENU_CALLBACK,
+  );
+  $items['edit/form/%/%/%/%/%'] = array(
+    'route_name' => 'edit.field_form',
+    'theme callback' => 'ajax_base_page_theme',
+    'type' => MENU_CALLBACK,
+  );
+
+  return $items;
+}
+
 /**
  * Implements hook_permission().
  */

core/modules/edit/edit.routing.yml

@@ -2,10 +2,9 @@ edit.metadata:
   path: '/edit/metadata'
   defaults:
     _controller: '\Drupal\edit\EditController::metadata'
-  options:
-    _theme: ajax_base_page
   requirements:
     _permission: 'access in-place editing'
+
 edit.attachments:
   path: '/edit/attachments'
   defaults:
@@ -17,9 +16,6 @@ edit.field_form:
   path: '/edit/form/{entity_type}/{entity}/{field_name}/{langcode}/{view_mode_id}'
   defaults:
     _controller: '\Drupal\edit\EditController::fieldForm'
-  options:
-    _access_mode: 'ALL'
-    _theme: ajax_base_page
   requirements:
     _permission: 'access in-place editing'
     _access_edit_entity_field: 'TRUE'

core/modules/editor/editor.module

@@ -139,6 +139,21 @@ function editor_library_info() {
   return $libraries;
 }
 
+/**
+ * Implements hook_menu().
+ */
+function editor_menu() {
+  // @todo Remove this menu item in http://drupal.org/node/1954892 when theme
+  //   callbacks are replaced with something else.
+  $items['editor/%/%/%/%/%'] = array(
+    'route_name' => 'editor.field_untransformed_text',
+    'theme callback' => 'ajax_base_page_theme',
+    'type' => MENU_CALLBACK,
+  );
+
+  return $items;
+}
+
 /**
  * Implements hook_form_FORM_ID_alter().
  */

core/modules/editor/editor.routing.yml

@@ -2,8 +2,6 @@ editor.field_untransformed_text:
   path: '/editor/{entity_type}/{entity}/{field_name}/{langcode}/{view_mode_id}'
   defaults:
     _controller: '\Drupal\editor\EditorController::getUntransformedText'
-  options:
-    _theme: ajax_base_page
   requirements:
     _permission: 'access in-place editing'
     _access_edit_entity_field: 'TRUE'

core/modules/file/file.module

@@ -37,6 +37,21 @@ function file_help($path, $arg) {
   }
 }
 
+/**
+ * Implements hook_menu().
+ */
+function file_menu() {
+  $items = array();
+
+  $items['file/ajax'] = array(
+    'route_name' => 'file.ajax_upload',
+    'theme callback' => 'ajax_base_page_theme',
+    'type' => MENU_CALLBACK,
+  );
+
+  return $items;
+}
+
 /**
  * Implements hook_element_info().
  *

core/modules/file/file.routing.yml

@@ -2,8 +2,6 @@ file.ajax_upload:
   path: '/file/ajax'
   defaults:
     _controller: '\Drupal\file\Controller\FileWidgetAjaxController::upload'
-  options:
-    _theme: ajax_base_page
   requirements:
     _permission: 'access content'
 

core/modules/search/lib/Drupal/search/Tests/SearchPageOverrideTest.php

@@ -38,7 +38,7 @@ function setUp() {
 
     // Enable the extra type module for searching.
     \Drupal::config('search.settings')->set('active_plugins', array('node_search', 'user_search', 'search_extra_type_search'))->save();
-    \Drupal::service('router.builder')->rebuild();
+    \Drupal::state()->set('menu_rebuild_needed', TRUE);
   }
 
   function testSearchPageHook() {

core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutLinksTest.php

@@ -145,7 +145,6 @@ function testShortcutLinkDelete() {
    */
   function testNoShortcutLink() {
     // Change to a theme that displays shortcuts.
-    theme_enable(array('seven'));
     \Drupal::config('system.theme')
       ->set('default', 'seven')
       ->save();
@@ -158,9 +157,8 @@ function testNoShortcutLink() {
     $this->assertNoRaw('add-shortcut', 'Add to shortcuts link was not shown on a page the user does not have access to.');
 
     // Verify that the testing mechanism works by verifying the shortcut
-    // link appears on admin/people.
-    $this->drupalGet('admin/people');
+    // link appears on admin/content/node.
+    $this->drupalGet('admin/content/node');
     $this->assertRaw('add-shortcut', 'Add to shortcuts link was shown on a page the user does have access to.');
   }
-
 }

core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutTestBase.php

@@ -69,7 +69,7 @@ function setUp() {
     }
 
     // Create users.
-    $this->admin_user = $this->drupalCreateUser(array('access toolbar', 'administer shortcuts', 'view the administration theme', 'create article content', 'create page content', 'access content overview', 'administer users'));
+    $this->admin_user = $this->drupalCreateUser(array('access toolbar', 'administer shortcuts', 'view the administration theme', 'create article content', 'create page content', 'access content overview'));
     $this->shortcut_user = $this->drupalCreateUser(array('customize shortcut links', 'switch shortcut sets'));
 
     // Create a node.

core/modules/system/lib/Drupal/system/Tests/Menu/MenuRouterTest.php

@@ -481,9 +481,18 @@ public function testThemeIntegration() {
     $this->initializeTestThemeConfiguration();
     $this->doTestThemeCallbackFakeTheme();
 
+    $this->initializeTestThemeConfiguration();
+    $this->doTestHookCustomTheme();
+
+    $this->initializeTestThemeConfiguration();
+    $this->doTestThemeCallbackHookCustomTheme();
+
     $this->initializeTestThemeConfiguration();
     $this->doTestThemeCallbackAdministrative();
 
+    $this->initializeTestThemeConfiguration();
+    $this->doTestThemeCallbackInheritance();
+
     $this->initializeTestThemeConfiguration();
     $this->doTestThemeCallbackNoThemeRequested();
 
@@ -507,17 +516,27 @@ protected function initializeTestThemeConfiguration() {
   }
 
   /**
-   * Test the theme negotiation when it is set to use an administrative theme.
+   * Test the theme callback when it is set to use an administrative theme.
    */
   protected function doTestThemeCallbackAdministrative() {
     theme_enable(array($this->admin_theme));
     $this->drupalGet('menu-test/theme-callback/use-admin-theme');
-    $this->assertText('Active theme: seven. Actual theme: seven.', 'The administrative theme can be correctly set in a theme negotiation.');
+    $this->assertText('Custom theme: seven. Actual theme: seven.', 'The administrative theme can be correctly set in a theme callback.');
+    $this->assertRaw('seven/style.css', "The administrative theme's CSS appears on the page.");
+  }
+
+  /**
+   * Test that the theme callback is properly inherited.
+   */
+  protected function doTestThemeCallbackInheritance() {
+    theme_enable(array($this->admin_theme));
+    $this->drupalGet('menu-test/theme-callback/use-admin-theme/inheritance');
+    $this->assertText('Custom theme: seven. Actual theme: seven. Theme callback inheritance is being tested.', 'Theme callback inheritance correctly uses the administrative theme.');
     $this->assertRaw('seven/style.css', "The administrative theme's CSS appears on the page.");
   }
 
   /**
-   * Test the theme negotiation when the site is in maintenance mode.
+   * Test the theme callback when the site is in maintenance mode.
    */
   protected function doTestThemeCallbackMaintenanceMode() {
     $this->container->get('state')->set('system.maintenance_mode', TRUE);
@@ -532,44 +551,76 @@ protected function doTestThemeCallbackMaintenanceMode() {
     $admin_user = $this->drupalCreateUser(array('access site in maintenance mode'));
     $this->drupalLogin($admin_user);
     $this->drupalGet('menu-test/theme-callback/use-admin-theme');
-    $this->assertText('Active theme: seven. Actual theme: seven.', 'The theme negotiation system is correctly triggered for an administrator when the site is in maintenance mode.');
+    $this->assertText('Custom theme: seven. Actual theme: seven.', 'The theme callback system is correctly triggered for an administrator when the site is in maintenance mode.');
     $this->assertRaw('seven/style.css', "The administrative theme's CSS appears on the page.");
 
     $this->container->get('state')->set('system.maintenance_mode', FALSE);
   }
 
   /**
-   * Test the theme negotiation when it is set to use an optional theme.
+   * Test the theme callback when it is set to use an optional theme.
    */
   protected function doTestThemeCallbackOptionalTheme() {
     // Request a theme that is not enabled.
     $this->drupalGet('menu-test/theme-callback/use-stark-theme');
-    $this->assertText('Active theme: bartik. Actual theme: bartik.', 'The theme negotiation system falls back on the default theme when a theme that is not enabled is requested.');
+    $this->assertText('Custom theme: NONE. Actual theme: bartik.', 'The theme callback system falls back on the default theme when a theme that is not enabled is requested.');
     $this->assertRaw('bartik/css/style.css', "The default theme's CSS appears on the page.");
 
     // Now enable the theme and request it again.
     theme_enable(array($this->alternate_theme));
     $this->drupalGet('menu-test/theme-callback/use-stark-theme');
-    $this->assertText('Active theme: stark. Actual theme: stark.', 'The theme negotiation system uses an optional theme once it has been enabled.');
+    $this->assertText('Custom theme: stark. Actual theme: stark.', 'The theme callback system uses an optional theme once it has been enabled.');
     $this->assertRaw('stark/css/layout.css', "The optional theme's CSS appears on the page.");
   }
 
   /**
-   * Test the theme negotiation when it is set to use a theme that does not exist.
+   * Test the theme callback when it is set to use a theme that does not exist.
    */
   protected function doTestThemeCallbackFakeTheme() {
     $this->drupalGet('menu-test/theme-callback/use-fake-theme');
-    $this->assertText('Active theme: bartik. Actual theme: bartik.', 'The theme negotiation system falls back on the default theme when a theme that does not exist is requested.');
+    $this->assertText('Custom theme: NONE. Actual theme: bartik.', 'The theme callback system falls back on the default theme when a theme that does not exist is requested.');
     $this->assertRaw('bartik/css/style.css', "The default theme's CSS appears on the page.");
   }
 
   /**
-   * Test the theme negotiation when no theme is requested.
+   * Test the theme callback when no theme is requested.
    */
   protected function doTestThemeCallbackNoThemeRequested() {
     $this->drupalGet('menu-test/theme-callback/no-theme-requested');
-    $this->assertText('Active theme: bartik. Actual theme: bartik.', 'The theme negotiation system falls back on the default theme when no theme is requested.');
+    $this->assertText('Custom theme: NONE. Actual theme: bartik.', 'The theme callback system falls back on the default theme when no theme is requested.');
     $this->assertRaw('bartik/css/style.css', "The default theme's CSS appears on the page.");
   }
 
+  /**
+   * Test that hook_custom_theme() can control the theme of a page.
+   */
+  protected function doTestHookCustomTheme() {
+    // Trigger hook_custom_theme() to dynamically request the Stark theme for
+    // the requested page.
+    \Drupal::state()->set('menu_test.hook_custom_theme_name', $this->alternate_theme);
+    theme_enable(array($this->alternate_theme, $this->admin_theme));
+
+    // Visit a page that does not implement a theme callback. The above request
+    // should be honored.
+    $this->drupalGet('menu-test/no-theme-callback');
+    $this->assertText('Custom theme: stark. Actual theme: stark.', 'The result of hook_custom_theme() is used as the theme for the current page.');
+    $this->assertRaw('stark/css/layout.css', "The Stark theme's CSS appears on the page.");
+  }
+
+  /**
+   * Test that the theme callback wins out over hook_custom_theme().
+   */
+  protected function doTestThemeCallbackHookCustomTheme() {
+    // Trigger hook_custom_theme() to dynamically request the Stark theme for
+    // the requested page.
+    \Drupal::state()->set('menu_test.hook_custom_theme_name', $this->alternate_theme);
+    theme_enable(array($this->alternate_theme, $this->admin_theme));
+
+    // The menu "theme callback" should take precedence over a value set in
+    // hook_custom_theme().
+    $this->drupalGet('menu-test/theme-callback/use-admin-theme');
+    $this->assertText('Custom theme: seven. Actual theme: seven.', 'The result of hook_custom_theme() does not override what was set in a theme callback.');
+    $this->assertRaw('seven/style.css', "The Seven theme's CSS appears on the page.");
+  }
+
 }

core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php

@@ -178,7 +178,7 @@ function testThemeSettings() {
    * Test the administration theme functionality.
    */
   function testAdministrationTheme() {
-    theme_enable(array('bartik', 'seven'));
+    theme_enable(array('seven'));
 
     // Enable an administration theme and show it on the node admin pages.
     $edit = array(

core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php

@@ -118,17 +118,6 @@ function testPreprocessForSuggestions() {
     }
   }
 
-  /**
-   * Tests the priority of some theme negotiators.
-   */
-  public function testNegotiatorPriorities() {
-    $this->drupalGet('theme-test/priority');
-
-    // Ensure that the custom theme negotiator was not able to set the theme.
-
-    $this->assertNoText('Theme hook implementor=test_theme_theme_test__suggestion(). Foo=template_preprocess_theme_test', 'Theme hook suggestion ran with data available from a preprocess function for the base hook.');
-  }
-
   /**
    * Ensure page-front template suggestion is added when on front page.
    */
@@ -279,4 +268,5 @@ function testPreprocessHtml() {
     $this->assertText('theme test page bottom markup', 'Modules are able to set the page bottom region.');
   }
 
+
 }

core/modules/system/lib/Drupal/system/Theme/BatchNegotiator.php

-<?php
-
-/**
- * @file
- * Contains \Drupal\system\Theme\BatchNegotiator.
- */
-
-namespace Drupal\system\Theme;
-
-use Drupal\Core\Batch\BatchStorageInterface;
-use Drupal\Core\Theme\ThemeNegotiatorInterface;
-use Symfony\Cmf\Component\Routing\RouteObjectInterface;
-use Symfony\Component\HttpFoundation\Request;
-
-/**
- * Sets the active theme for the batch page.
- */
-class BatchNegotiator implements ThemeNegotiatorInterface {
-
-  /**
-   * The batch storage.
-   *
-   * @var \Drupal\Core\Batch\BatchStorageInterface
-   */
-  protected $batchStorage;
-
-  /**
-   * Constructs a BatchNegotiator.
-   *
-   * @param \Drupal\Core\Batch\BatchStorageInterface $batch_storage
-   *   The batch storage.
-   */
-  public function __construct(BatchStorageInterface $batch_storage) {
-    $this->batchStorage = $batch_storage;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function determineActiveTheme(Request $request) {
-    if ($request->attributes->get(RouteObjectInterface::ROUTE_NAME) == 'system.batch_page') {
-      // Retrieve the current state of the batch.
-      $batch = &batch_get();
-      if (!$batch && $request->request->has('id')) {
-        $batch = $this->batchStorage->load($request->request->get('id'));
-      }
-      // Use the same theme as the page that started the batch.
-      if (!empty($batch['theme'])) {
-        return $batch['theme'];
-      }
-    }
-  }
-
-}

core/modules/system/system.api.php

@@ -1425,6 +1425,36 @@ function hook_template_preprocess_default_variables_alter(&$variables) {
   $variables['is_admin'] = user_access('access administration pages');
 }
 
+/**
+ * Return the machine-readable name of the theme to use for the current page.
+ *
+ * This hook can be used to dynamically set the theme for the current page
+ * request. It should be used by modules which need to override the theme
+ * based on dynamic conditions (for example, a module which allows the theme to
+ * be set based on the current user's role). The return value of this hook will
+ * be used on all pages except those which have a valid per-page or per-section
+ * theme set via a theme callback function in hook_menu(); the themes on those
+ * pages can only be overridden using hook_menu_alter().
+ *
+ * Note that returning different themes for the same path may not work with page
+ * caching. This is most likely to be a problem if an anonymous user on a given
+ * path could have different themes returned under different conditions.
+ *
+ * Since only one theme can be used at a time, the last (i.e., highest
+ * weighted) module which returns a valid theme name from this hook will
+ * prevail.
+ *
+ * @return
+ *   The machine-readable name of the theme that should be used for the current
+ *   page request. The value returned from this function will only have an
+ *   effect if it corresponds to a currently-active theme on the site. Do not
+ *   return a value if you do not wish to set a custom theme.
+ */
+function hook_custom_theme() {
+  // Allow the user to request a particular theme via a query parameter.
+  return \Drupal::request()->query->get('theme');
+}
+
 /**
  * Log an event message.
  *

core/modules/system/system.install

@@ -824,6 +824,20 @@ function system_schema() {
         'not null' => TRUE,
         'default' => '',
       ),
+      'theme_callback' => array(
+        'description' => 'A function which returns the name of the theme that will be used to render this page. If left empty, the default theme will be used.',
+        'type' => 'varchar',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'theme_arguments' => array(
+        'description' => 'A serialized array of arguments for the theme callback.',
+        'type' => 'varchar',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+      ),
       'type' => array(
         'description' => 'Numeric representation of the type of the menu item, like MENU_LOCAL_TASK.',
         'type' => 'int',

core/modules/system/system.module

@@ -613,6 +613,12 @@ function system_element_info() {
  * Implements hook_menu().
  */
 function system_menu() {
+  $items['system/ajax'] = array(
+    'title' => 'AHAH callback',
+    'route_name' => 'system.ajax',
+    'theme callback' => 'ajax_base_page_theme',
+    'type' => MENU_CALLBACK,
+  );
   $items['admin'] = array(
     'title' => 'Administration',
     'route_name' => 'system.admin',
@@ -806,6 +812,13 @@ function system_menu() {
     'route_name' => 'system.status',
   );
 
+  // Default page for batch operations.
+  $items['batch'] = array(
+    'route_name' => 'system.batch_page',
+    'theme callback' => '_system_batch_theme',
+    'type' => MENU_CALLBACK,
+  );
+
   return $items;
 }
 
@@ -857,6 +870,21 @@ function system_theme_suggestions_region(array $variables) {
   return $suggestions;
 }
 
+/**
+ * Theme callback for the default batch page.
+ */
+function _system_batch_theme() {
+  // Retrieve the current state of the batch.
+  $batch = &batch_get();
+  if (!$batch && isset($_REQUEST['id'])) {
+    $batch = \Drupal::service('batch.storage')->load($_REQUEST['id']);
+  }
+  // Use the same theme as the page that started the batch.
+  if (!empty($batch['theme'])) {
+    return $batch['theme'];
+  }
+}
+
 /**
  * Implements hook_library_info().
  */
@@ -2103,6 +2131,19 @@ function system_page_build(&$page) {
   }
 }
 
+/**
+ * Implements hook_custom_theme().
+ */
+function system_custom_theme() {
+  if (drupal_container()->isScopeActive('request')) {
+    $request = \Drupal::request();
+    $path = $request->attributes->get('_system_path');
+    if (user_access('view the administration theme') && path_is_admin($path)) {
+      return \Drupal::config('system.theme')->get('admin');
+    }
+  }
+}
+
 /**
  * Implements hook_form_FORM_ID_alter().
  */

core/modules/system/system.routing.yml

@@ -2,8 +2,6 @@ system.ajax:
   path: '/system/ajax'
   defaults:
     _controller: '\Drupal\system\Controller\FormAjaxController::content'
-  options:
-    _theme: ajax_base_page
   requirements:
     _access: 'TRUE'