diff --git a/core/modules/file/file.module b/core/modules/file/file.module
index 7b92200..ac9086a 100644
--- a/core/modules/file/file.module
+++ b/core/modules/file/file.module
@@ -720,101 +720,6 @@ function file_cron() {
 }
 
 /**
- * Ajax callback: Processes file uploads and deletions.
- *
- * This rebuilds the form element for a particular field item. As long as the
- * form processing is properly encapsulated in the widget element the form
- * should rebuild correctly using FAPI without the need for additional callbacks
- * or processing.
- *
- * @see file_menu()
- */
-function file_ajax_upload() {
-  $form_parents = func_get_args();
-  $form_build_id = (string) array_pop($form_parents);
-
-  $request = \Drupal::request();
-  if (!$request->request->has('form_build_id') || $form_build_id != $request->request->get('form_build_id')) {
-    // Invalid request.
-    drupal_set_message(t('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@size) that this server supports.', array('@size' => format_size(file_upload_max_size()))), 'error');
-    $response = new AjaxResponse();
-    return $response->addCommand(new ReplaceCommand(NULL, theme('status_messages')));
-  }
-
-  list($form, $form_state) = ajax_get_form();
-
-  if (!$form) {
-    // Invalid form_build_id.
-    drupal_set_message(t('An unrecoverable error occurred. Use of this form has expired. Try reloading the page and submitting again.'), 'error');
-    $response = new AjaxResponse();
-    return $response->addCommand(new ReplaceCommand(NULL, theme('status_messages')));
-  }
-
-  // Get the current element and count the number of files.
-  $current_element = $form;
-  foreach ($form_parents as $parent) {
-    $current_element = $current_element[$parent];
-  }
-  $current_file_count = isset($current_element['#file_upload_delta']) ? $current_element['#file_upload_delta'] : 0;
-
-  // Process user input. $form and $form_state are modified in the process.
-  drupal_process_form($form['#form_id'], $form, $form_state);
-
-  // Retrieve the element to be rendered.
-  foreach ($form_parents as $parent) {
-    $form = $form[$parent];
-  }
-
-  // Add the special Ajax class if a new file was added.
-  if (isset($form['#file_upload_delta']) && $current_file_count < $form['#file_upload_delta']) {
-    $form[$current_file_count]['#attributes']['class'][] = 'ajax-new-content';
-  }
-  // Otherwise just add the new content class on a placeholder.
-  else {
-    $form['#suffix'] .= '<span class="ajax-new-content"></span>';
-  }
-
-  $form['#prefix'] .= theme('status_messages');
-  $output = drupal_render($form);
-  $js = drupal_add_js();
-  $settings = drupal_merge_js_settings($js['settings']['data']);
-
-  $response = new AjaxResponse();
-  return $response->addCommand(new ReplaceCommand(NULL, $output, $settings));
-}
-
-/**
- * Ajax callback: Retrieves upload progress.
- *
- * @param $key
- *   The unique key for this upload process.
- */
-function file_ajax_progress($key) {
-  $progress = array(
-    'message' => t('Starting upload...'),
-    'percentage' => -1,
-  );
-
-  $implementation = file_progress_implementation();
-  if ($implementation == 'uploadprogress') {
-    $status = uploadprogress_get_info($key);
-    if (isset($status['bytes_uploaded']) && !empty($status['bytes_total'])) {
-      $progress['message'] = t('Uploading... (@current of @total)', array('@current' => format_size($status['bytes_uploaded']), '@total' => format_size($status['bytes_total'])));
-      $progress['percentage'] = round(100 * $status['bytes_uploaded'] / $status['bytes_total']);
-    }
-  }
-  elseif ($implementation == 'apc') {
-    $status = apc_fetch('upload_' . $key);
-    if (isset($status['current']) && !empty($status['total'])) {
-      $progress['message'] = t('Uploading... (@current of @total)', array('@current' => format_size($status['current']), '@total' => format_size($status['total'])));
-      $progress['percentage'] = round(100 * $status['current'] / $status['total']);
-    }
-  }
-
-  return new JsonResponse($progress);
-}
-
-/**
  * Determines the preferred upload progress implementation.
  *
  * @return
diff --git a/core/modules/file/lib/Drupal/file/Controller/FileWidgetAjaxController.php b/core/modules/file/lib/Drupal/file/Controller/FileWidgetAjaxController.php
index efd42e5..da36c07 100644
--- a/core/modules/file/lib/Drupal/file/Controller/FileWidgetAjaxController.php
+++ b/core/modules/file/lib/Drupal/file/Controller/FileWidgetAjaxController.php
@@ -21,7 +21,7 @@
 class FileWidgetAjaxController extends FormAjaxController {
 
   /**
-   * Handle form AJAX request.
+   * Processes AJAX file uploads.
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
    *  The current request object.
@@ -81,7 +81,7 @@ public function upload(Request $request) {
   }
 
   /**
-   * Handle AJAX upload progress request.
+   * Returns the progress status for a file upload process.
    *
    * @param string $key
    *   The unique key for this upload process.