Issue #2072369 by tim.plunkett: Modernize book.module forms.

core/modules/book/book.routing.yml

@@ -15,6 +15,6 @@ book_admin:
 book_settings:
   pattern: '/admin/structure/book/settings'
   defaults:
-    _form: 'Drupal\book\BookSettingsForm'
+    _form: 'Drupal\book\Form\BookSettingsForm'
   requirements:
     _permission: 'administer site configuration'

core/modules/book/lib/Drupal/book/BookSettingsForm.php → core/modules/book/lib/Drupal/book/Form/BookSettingsForm.php

@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\book\BookSettingsForm.
+ * Contains \Drupal\book\Form\BookSettingsForm.
  */
 
-namespace Drupal\book;
+namespace Drupal\book\Form;
 
 use Drupal\system\SystemConfigFormBase;
 
@@ -15,29 +15,29 @@
 class BookSettingsForm extends SystemConfigFormBase {
 
   /**
-   * Implements \Drupal\Core\Form\FormInterface::getFormID().
+   * {@inheritdoc}
    */
   public function getFormID() {
     return 'book_admin_settings';
   }
 
   /**
-   * Implements \Drupal\Core\Form\FormInterface::buildForm().
+   * {@inheritdoc}
    */
   public function buildForm(array $form, array &$form_state) {
     $types = node_type_get_names();
     $config = $this->configFactory->get('book.settings');
     $form['book_allowed_types'] = array(
       '#type' => 'checkboxes',
-      '#title' => t('Content types allowed in book outlines'),
+      '#title' => $this->t('Content types allowed in book outlines'),
       '#default_value' => $config->get('allowed_types'),
       '#options' => $types,
-      '#description' => t('Users with the %outline-perm permission can add all content types.', array('%outline-perm' => t('Administer book outlines'))),
+      '#description' => $this->t('Users with the %outline-perm permission can add all content types.', array('%outline-perm' => $this->t('Administer book outlines'))),
       '#required' => TRUE,
     );
     $form['book_child_type'] = array(
       '#type' => 'radios',
-      '#title' => t('Content type for child pages'),
+      '#title' => $this->t('Content type for child pages'),
       '#default_value' => $config->get('child_type'),
       '#options' => $types,
       '#required' => TRUE,
@@ -48,19 +48,19 @@ public function buildForm(array $form, array &$form_state) {
   }
 
   /**
-   * Implements \Drupal\Core\Form\FormInterface::validateForm().
+   * {@inheritdoc}
    */
   public function validateForm(array &$form, array &$form_state) {
     $child_type = $form_state['values']['book_child_type'];
     if (empty($form_state['values']['book_allowed_types'][$child_type])) {
-      form_set_error('book_child_type', t('The content type for the %add-child link must be one of those selected as an allowed book outline type.', array('%add-child' => t('Add child page'))));
+      form_set_error('book_child_type', $this->t('The content type for the %add-child link must be one of those selected as an allowed book outline type.', array('%add-child' => $this->t('Add child page'))));
     }
 
     parent::validateForm($form, $form_state);
   }
 
   /**
-   * Implements \Drupal\Core\Form\FormInterface::submitForm().
+   * {@inheritdoc}
    */
   public function submitForm(array &$form, array &$form_state) {
     $allowed_types = array_filter($form_state['values']['book_allowed_types']);