Implements \Drupal\ckeditor\Plugin\CKEditorPluginConfigurableInterface::settingsForm().
Overrides CKEditorPluginConfigurableInterface::settingsForm
public function settingsForm(array $form, array &$form_state, Editor $editor) {
  // Defaults.
  $config = array(
    'styles' => '',
  );
  if (isset($editor->settings['plugins']['stylescombo'])) {
    $config = $editor->settings['plugins']['stylescombo'];
  }
  $form['styles'] = array(
    '#title' => t('Styles'),
    '#title_display' => 'invisible',
    '#type' => 'textarea',
    '#default_value' => $config['styles'],
    '#description' => t('A list of classes that will be provided in the "Styles" dropdown. Enter one class on each line in the format: element.class|Label. Example: h1.title|Title.<br />These styles should be available in your theme\'s CSS file.'),
    '#attached' => array(
      'library' => array(
        array(
          'ckeditor',
          'drupal.ckeditor.stylescombo.admin',
        ),
      ),
    ),
    '#element_validate' => array(
      array(
        $this,
        'validateStylesValue',
      ),
    ),
  );
  return $form;
}