diff --git a/core/modules/book/book.module b/core/modules/book/book.module
index db5b697..7248352 100644
--- a/core/modules/book/book.module
+++ b/core/modules/book/book.module
@@ -351,59 +351,6 @@ function book_pick_book_nojs_submit($form, &$form_state) {
 }
 
 /**
- * Builds the parent selection form element for the node form or outline tab.
- *
- * This function is also called when generating a new set of options during the
- * Ajax callback, so an array is returned that can be used to replace an
- * existing form element.
- *
- * @param $book_link
- *   A fully loaded menu link that is part of the book hierarchy.
- *
- * @return
- *   A parent selection form element.
- */
-function _book_parent_select($book_link) {
-  if (Drupal::config('menu.settings')->get('override_parent_selector')) {
-    return array();
-  }
-  // Offer a message or a drop-down to choose a different parent page.
-  $form = array(
-    '#type' => 'hidden',
-    '#value' => -1,
-    '#prefix' => '<div id="edit-book-plid-wrapper">',
-    '#suffix' => '</div>',
-  );
-
-  if ($book_link['nid'] === $book_link['bid']) {
-    // This is a book - at the top level.
-    if ($book_link['original_bid'] === $book_link['bid']) {
-      $form['#prefix'] .= '<em>' . t('This is the top-level page in this book.') . '</em>';
-    }
-    else {
-      $form['#prefix'] .= '<em>' . t('This will be the top-level page in this book.') . '</em>';
-    }
-  }
-  elseif (!$book_link['bid']) {
-    $form['#prefix'] .= '<em>' . t('No book selected.') . '</em>';
-  }
-  else {
-    $form = array(
-      '#type' => 'select',
-      '#title' => t('Parent item'),
-      '#default_value' => $book_link['plid'],
-      '#description' => t('The parent page in the book. The maximum depth for a book and all child pages is !maxdepth. Some pages in the selected book may not be available as parents if selecting them would exceed this limit.', array('!maxdepth' => MENU_MAX_DEPTH)),
-      '#options' => book_toc($book_link['bid'], $book_link['parent_depth_limit'], array($book_link['mlid'])),
-      '#attributes' => array('class' => array('book-title-select')),
-      '#prefix' => '<div id="edit-book-plid-wrapper">',
-      '#suffix' => '</div>',
-    );
-  }
-
-  return $form;
-}
-
-/**
  * Renders a new parent page select element when the book selection changes.
  *
  * This function is called via Ajax when the selected book is changed on a node
diff --git a/core/modules/book/book.services.yml b/core/modules/book/book.services.yml
index a5f9d5a..64e560e 100644
--- a/core/modules/book/book.services.yml
+++ b/core/modules/book/book.services.yml
@@ -1,4 +1,4 @@
 services:
   book.manager:
     class: Drupal\book\BookManager
-    arguments: ['@database', '@plugin.manager.entity', '@string_translation']
+    arguments: ['@database', '@plugin.manager.entity', '@string_translation', '@config.factory']
diff --git a/core/modules/book/lib/Drupal/book/BookManager.php b/core/modules/book/lib/Drupal/book/BookManager.php
index 5b89ea3..237ab6f 100644
--- a/core/modules/book/lib/Drupal/book/BookManager.php
+++ b/core/modules/book/lib/Drupal/book/BookManager.php
@@ -11,8 +11,8 @@
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\Core\Config\ConfigFactory;
 use Drupal\node\NodeInterface;
-use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Book Manager Service.
@@ -41,6 +41,13 @@ class BookManager {
   protected $translation;
 
   /**
+   * The config factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactory
+   */
+  protected $configFactory;
+
+  /**
    * Books Array.
    *
    * @var array
@@ -50,10 +57,11 @@ class BookManager {
   /**
    * Constructs a BookManager object.
    */
-  public function __construct(Connection $connection, EntityManager $entityManager, TranslationInterface $translation) {
+  public function __construct(Connection $connection, EntityManager $entityManager, TranslationInterface $translation, ConfigFactory $configFactory) {
     $this->connection = $connection;
     $this->entityManager = $entityManager;
     $this->translation =  $translation;
+    $this->ConfigFactory = $configFactory;
   }
 
   /**
@@ -134,7 +142,7 @@ public function linkDefaults($nid) {
   /**
    * Finds the depth limit for items in the parent select.
    *
-   * @param $book_link
+   * @param array $book_link
    *   A fully loaded menu link that is part of the book hierarchy.
    *
    * @return int
@@ -186,7 +194,7 @@ public function addFormElements(array $form, array &$form_state, NodeInterface $
       );
     }
 
-    $form['book']['plid'] = _book_parent_select($node->book);
+    $form['book']['plid'] = $this->addParentSelectFormElements($node->book);
 
     // @see _book_admin_table_tree(). The weight may be larger than 15.
     $form['book']['weight'] = array(
@@ -346,12 +354,13 @@ public function updateOutline(NodeInterface $node) {
    *
    * @return string
    *   The translated string.
+   *
+   *   @todo Remove when https://drupal.org/node/2018411 is in.
    */
   protected function t($string, array $args = array(), array $options = array()) {
     return $this->translation->translate($string, $args, $options);
   }
 
-
   /**
    * Generates the corresponding menu name from a book ID.
    *
@@ -368,7 +377,7 @@ public function createMenuName($id) {
   /**
    * Updates the book ID of a page and its children when it moves to a new book.
    *
-   * @param $book_link
+   * @param array $book_link
    *   A fully loaded menu link that is part of the book hierarchy.
    */
   function updateID($book_link) {
@@ -387,4 +396,57 @@ function updateID($book_link) {
     }
   }
 
+  /**
+   * Builds the parent selection form element for the node form or outline tab.
+   *
+   * This function is also called when generating a new set of options during the
+   * Ajax callback, so an array is returned that can be used to replace an
+   * existing form element.
+   *
+   * @param array $book_link
+   *   A fully loaded menu link that is part of the book hierarchy.
+   *
+   * @return
+   *   A parent selection form element.
+   */
+  function addParentSelectFormElements($book_link) {
+    if ($this->configFactory('menu.settings')->get('override_parent_selector')) {
+      return array();
+    }
+    // Offer a message or a drop-down to choose a different parent page.
+    $form = array(
+      '#type' => 'hidden',
+      '#value' => -1,
+      '#prefix' => '<div id="edit-book-plid-wrapper">',
+      '#suffix' => '</div>',
+    );
+
+    if ($book_link['nid'] === $book_link['bid']) {
+      // This is a book - at the top level.
+      if ($book_link['original_bid'] === $book_link['bid']) {
+        $form['#prefix'] .= '<em>' . t('This is the top-level page in this book.') . '</em>';
+      }
+      else {
+        $form['#prefix'] .= '<em>' . t('This will be the top-level page in this book.') . '</em>';
+      }
+    }
+    elseif (!$book_link['bid']) {
+      $form['#prefix'] .= '<em>' . t('No book selected.') . '</em>';
+    }
+    else {
+      $form = array(
+        '#type' => 'select',
+        '#title' => t('Parent item'),
+        '#default_value' => $book_link['plid'],
+        '#description' => t('The parent page in the book. The maximum depth for a book and all child pages is !maxdepth. Some pages in the selected book may not be available as parents if selecting them would exceed this limit.', array('!maxdepth' => MENU_MAX_DEPTH)),
+        '#options' => book_toc($book_link['bid'], $book_link['parent_depth_limit'], array($book_link['mlid'])),
+        '#attributes' => array('class' => array('book-title-select')),
+        '#prefix' => '<div id="edit-book-plid-wrapper">',
+        '#suffix' => '</div>',
+      );
+    }
+
+    return $form;
+  }
+
 }