diff --git a/core/includes/batch.inc b/core/includes/batch.inc
index 99d8bc3..974fda0 100644
--- a/core/includes/batch.inc
+++ b/core/includes/batch.inc
@@ -74,7 +74,7 @@ function _batch_page(Request $request) {
     case 'do_nojs':
       // Display the full progress page on startup and on each additional
       // non-JavaScript iteration.
-      $current_set = _batch_current_set();
+      $current_set = \Drupal::service('batch.processor')->currentSet();
       $build['#title'] = $current_set['title'];
       $build['content'] = _batch_progress_page();
       break;
@@ -84,8 +84,9 @@ function _batch_page(Request $request) {
       return _batch_do();
 
     case 'finished':
-      // _batch_finished() returns a RedirectResponse.
-      return _batch_finished();
+      // \Drupal\Core\Batch\BatchProcessorInterface::finished() returns a
+      // RedirectResponse.
+      return \Drupal::service('batch.processor')->finished();
   }
 
   return $build;
@@ -95,11 +96,11 @@ function _batch_page(Request $request) {
  * Does one execution pass with JavaScript and returns progress to the browser.
  *
  * @see _batch_progress_page_js()
- * @see _batch_process()
+ * @see \Drupal\Core\Batch\BatchProcessorInterface::process()
  */
 function _batch_do() {
   // Perform actual processing.
-  list($percentage, $message, $label) = _batch_process();
+  list($percentage, $message, $label) = \Drupal::service('batch.processor')->process();
 
   return new JsonResponse(array('status' => TRUE, 'percentage' => $percentage, 'message' => $message, 'label' => $label));
 }
@@ -107,12 +108,12 @@ function _batch_do() {
 /**
  * Outputs a batch processing page.
  *
- * @see _batch_process()
+ * @see \Drupal\Core\Batch\BatchProcessorInterface::process()
  */
 function _batch_progress_page() {
   $batch = &batch_get();
 
-  $current_set = _batch_current_set();
+  $current_set = \Drupal::service('batch.processor')->currentSet();
 
   $new_op = 'do_nojs';
 
@@ -143,7 +144,7 @@ function _batch_progress_page() {
     print $fallback;
 
     // Perform actual processing.
-    list($percentage, $message, $label) = _batch_process($batch);
+    list($percentage, $message, $label) = \Drupal::service('batch.processor')->process($batch);
     if ($percentage == 100) {
       $new_op = 'finished';
     }
@@ -201,83 +202,6 @@ function _batch_progress_page() {
 }
 
 /**
- * Processes sets in a batch.
- *
- * If the batch was marked for progressive execution (default), this executes as
- * many operations in batch sets until an execution time of 1 second has been
- * exceeded. It will continue with the next operation of the same batch set in
- * the next request.
- *
- * @return
- *   An array containing a completion value (in percent) and a status message.
- *
- * @deprecated Use \Drupal::service('batch.processor')->process() instead.
- */
-function _batch_process() {
-  return \Drupal::service('batch.processor')->process();
-}
-
-/**
- * Formats the percent completion for a batch set.
- *
- * @param $total
- *   The total number of operations.
- * @param $current
- *   The number of the current operation. This may be a floating point number
- *   rather than an integer in the case of a multi-step operation that is not
- *   yet complete; in that case, the fractional part of $current represents the
- *   fraction of the operation that has been completed.
- *
- * @return
- *   The properly formatted percentage, as a string. We output percentages
- *   using the correct number of decimal places so that we never print "100%"
- *   until we are finished, but we also never print more decimal places than
- *   are meaningful.
- *
- * @see _batch_process()
- *
- * @deprecated Use \Drupal\Core\Batch\Percentage::format() instead.
- */
-function _batch_api_percentage($total, $current) {
-  return Percentage::format($total, $current);
-}
-
-/**
- * Returns the batch set being currently processed.
- *
- * @deprecated Use \Drupal::service('batch.processor')->currentSet() instead.
- */
-function &_batch_current_set() {
-  return \Drupal::service('batch.processor')->currentSet();
-}
-
-/**
- * Retrieves the next set in a batch.
- *
- * If there is a subsequent set in this batch, assign it as the new set to
- * process and execute its form submit handler (if defined), which may add
- * further sets to this batch.
- *
- * @return
- *   TRUE if a subsequent set was found in the batch.
- *
- * @deprecated Use \Drupal::service('batch.processor')->nextSet() instead.
- */
-function _batch_next_set() {
-  return \Drupal::service('batch.processor')->nextSet();
-}
-
-/**
- * Ends the batch processing.
- *
- * Call the 'finished' callback of each batch set to allow custom handling of
- * the results and resolve page redirection.
- */
-function _batch_finished() {
-  \Drupal::service('batch.processor')->finished();
-}
-
-/**
  * Shutdown function: Stores the current batch data for the next request.
  *
  * @see _batch_page()
diff --git a/core/includes/form.inc b/core/includes/form.inc
index f06cb17..2551d88 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -1042,8 +1042,7 @@ function batch_process($redirect = NULL, $url = 'batch', $redirect_callback = NU
     else {
       // Non-progressive execution: bypass the whole progressbar workflow
       // and execute the batch in one pass.
-      require_once __DIR__ . '/batch.inc';
-      _batch_process();
+      \Drupal::service('batch.processor')->process();
     }
   }
 }
diff --git a/core/lib/Drupal/Core/Batch/BatchProcessor.php b/core/lib/Drupal/Core/Batch/BatchProcessor.php
index 56cc7f0..1b65da5 100644
--- a/core/lib/Drupal/Core/Batch/BatchProcessor.php
+++ b/core/lib/Drupal/Core/Batch/BatchProcessor.php
@@ -16,8 +16,6 @@
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\RequestStack;
 
-require_once DRUPAL_ROOT . '/core/includes/form.inc';
-
 /**
  * Provides a batch processor.
  */
@@ -137,7 +135,7 @@ public function process() {
       // When all operations in the current batch set are completed, browse
       // through the remaining sets, marking them 'successfully processed'
       // along the way, until we find a set that contains operations.
-      // _batch_next_set() executes form submit handlers stored in 'control'
+      // nextSet() executes form submit handlers stored in 'control'
       // sets (see form_execute_handlers()), which can in turn add new sets to
       // the batch.
       $set_changed = FALSE;
diff --git a/core/lib/Drupal/Core/Batch/BatchProcessorInterface.php b/core/lib/Drupal/Core/Batch/BatchProcessorInterface.php
index d5e3444..4ccb995 100644
--- a/core/lib/Drupal/Core/Batch/BatchProcessorInterface.php
+++ b/core/lib/Drupal/Core/Batch/BatchProcessorInterface.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\Core\Batch;
+use Symfony\Component\HttpFoundation\RedirectResponse;
 
 /**
  * Processes batch requests.
@@ -50,6 +51,9 @@ public function nextSet();
    *
    * Call the 'finished' callback of each batch set to allow custom handling of
    * the results and resolve page redirection.
+   *
+   * @return \Symfony\Component\HttpFoundation\RedirectResponse
+   *   A redirect response.
    */
   public function finished();
 
diff --git a/core/lib/Drupal/Core/Batch/Percentage.php b/core/lib/Drupal/Core/Batch/Percentage.php
index 6cb1bef..0eb30e2 100644
--- a/core/lib/Drupal/Core/Batch/Percentage.php
+++ b/core/lib/Drupal/Core/Batch/Percentage.php
@@ -29,7 +29,7 @@ class Percentage {
    *   until we are finished, but we also never print more decimal places than
    *   are meaningful.
    *
-   * @see _batch_process()
+   * @see \Drupal\Core\Batch\BatchProcessorInterface::process()
    */
   public static function format($total, $current) {
     if (!$total || $total == $current) {
diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index b1e2260..6e516fb 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -195,7 +195,8 @@ public function buildForm($form_id, FormStateInterface &$form_state) {
 
     if (isset($_SESSION['batch_form_state'])) {
       // We've been redirected here after a batch processing. The form has
-      // already been processed, but needs to be rebuilt. See _batch_finished().
+      // already been processed, but needs to be rebuilt. See
+      // \Drupal\Core\Batch\BatchProcessorInterface::finished().
       $form_state = $_SESSION['batch_form_state'];
       unset($_SESSION['batch_form_state']);
       return $this->rebuildForm($form_id, $form_state);
diff --git a/core/lib/Drupal/Core/Form/FormSubmitter.php b/core/lib/Drupal/Core/Form/FormSubmitter.php
index ab7e76e..f25f560 100644
--- a/core/lib/Drupal/Core/Form/FormSubmitter.php
+++ b/core/lib/Drupal/Core/Form/FormSubmitter.php
@@ -71,8 +71,9 @@ public function doSubmitForm(&$form, FormStateInterface &$form_state) {
 
       // Execution continues only for programmatic forms.
       // For 'regular' forms, we get redirected to the batch processing
-      // page. Form redirection will be handled in _batch_finished(),
-      // after the batch is processed.
+      // page. Form redirection will be handled in
+      // \Drupal\Core\Batch\BatchProcessorInterface::finished(), after the batch
+      // is processed.
     }
 
     // Set a flag to indicate the the form has been processed and executed.
@@ -113,7 +114,7 @@ public function executeSubmitHandlers(&$form, FormStateInterface &$form_state) {
       if (($batch = &$this->batchGet()) && !isset($batch['id'])) {
         // Some previous submit handler has set a batch. To ensure correct
         // execution order, store the call in a special 'control' batch set.
-        // See _batch_next_set().
+        // See \Drupal\Core\Batch\BatchProcessorInterface::nextSet().
         $batch['sets'][] = array('form_submit' => $callback);
         $batch['has_form_submits'] = TRUE;
       }