diff --git a/core/modules/config/config.admin.inc b/core/modules/config/config.admin.inc
index 9d6a605..95c72bc 100644
--- a/core/modules/config/config.admin.inc
+++ b/core/modules/config/config.admin.inc
@@ -10,6 +10,89 @@
 use Drupal\Core\Ajax\OpenModalDialogCommand;
 
 /**
+ * Helper function to construct the storage changes in a configuration synchronization form.
+ *
+ * @param array $form
+ *   The form structure to add to. Passed by reference.
+ * @param array $form_state
+ *   The current state of the form. Passed by reference.
+ * @param Drupal\Core\Config\StorageInterface $source_storage
+ *   The source storage to retrieve differences from.
+ * @param Drupal\Core\Config\StorageInterface $target_storage
+ *   The target storage to compare differences to.
+ */
+function config_admin_sync_form(array &$form, array &$form_state, StorageInterface $source_storage, StorageInterface $target_storage) {
+  $source_list = $source_storage->listAll();
+  if (empty($source_list)) {
+    $form['no_changes'] = array(
+      '#markup' => t('There is no configuration to import.'),
+    );
+    $form['actions']['#access'] = FALSE;
+    return $form;
+  }
+
+  $config_changes = config_sync_get_changes($source_storage, $target_storage);
+  if (empty($config_changes)) {
+    $form['no_changes'] = array(
+      '#markup' => t('There are no configuration changes.'),
+    );
+    return $form;
+  }
+
+  // Add the AJAX library to the form for dialog support.
+  $form['#attached']['library'][] = array('system', 'drupal.ajax');
+
+  foreach ($config_changes as $config_change_type => $config_files) {
+    if (empty($config_files)) {
+      continue;
+    }
+
+    // @todo A table caption would be more appropriate, but does not have the
+    //   visual importance of a heading.
+    $form[$config_change_type]['heading'] = array(
+      '#theme' => 'html_tag__h3',
+      '#tag' => 'h3',
+    );
+    switch ($config_change_type) {
+      case 'create':
+        $form[$config_change_type]['heading']['#value'] = format_plural(count($config_files), '@count new', '@count new');
+        break;
+
+      case 'change':
+        $form[$config_change_type]['heading']['#value'] = format_plural(count($config_files), '@count changed', '@count changed');
+        break;
+
+      case 'delete':
+        $form[$config_change_type]['heading']['#value'] = format_plural(count($config_files), '@count removed', '@count removed');
+        break;
+    }
+    $form[$config_change_type]['list'] = array(
+      '#theme' => 'table',
+      '#header' => array('Name', 'Operations'),
+    );
+
+    foreach ($config_files as $config_file) {
+      $links['view_diff'] = array(
+        'title' => t('View differences'),
+        'href' => 'admin/config/development/sync/diff/' . $config_file,
+        'attributes' => array(
+          'class' => array('use-ajax'),
+        ),
+      );
+      $form[$config_change_type]['list']['#rows'][] = array(
+        'name' => $config_file,
+        'operations' => array(
+          'data' => array(
+            '#type' => 'operations',
+            '#links' => $links,
+          ),
+        ),
+      );
+    }
+  }
+}
+
+/**
  * Page callback: Shows diff of specificed configuration file.
  *
  * @param string $config_file
diff --git a/core/modules/config/lib/Drupal/config/Form/ConfigAdminImportForm.php b/core/modules/config/lib/Drupal/config/Form/ConfigAdminImportForm.php
index 3c36e1e..8d1537a 100644
--- a/core/modules/config/lib/Drupal/config/Form/ConfigAdminImportForm.php
+++ b/core/modules/config/lib/Drupal/config/Form/ConfigAdminImportForm.php
@@ -85,74 +85,8 @@ public function buildForm(array $form, array &$form_state) {
       '#value' => t('Import all'),
     );
 
-    $source_list = $this->sourceStorage->listAll();
-    if (empty($source_list)) {
-      $form['no_changes'] = array(
-        '#markup' => t('There is no configuration to import.'),
-        );
-      $form['actions']['#access'] = FALSE;
-      return $form;
-    }
-
-    $config_changes = config_sync_get_changes($this->sourceStorage, $this->targetStorage);
-    if (empty($config_changes)) {
-      $form['no_changes'] = array(
-        '#markup' => t('There are no configuration changes.'),
-      );
-      return $form;
-    }
+    config_admin_sync_form($form, $form_state, $source_storage, $target_storage);
 
-    // Add the AJAX library to the form for dialog support.
-    $form['#attached']['library'][] = array('system', 'drupal.ajax');
-
-    foreach ($config_changes as $config_change_type => $config_files) {
-      if (empty($config_files)) {
-        continue;
-      }
-
-      // @todo A table caption would be more appropriate, but does not have the
-      //   visual importance of a heading.
-      $form[$config_change_type]['heading'] = array(
-        '#theme' => 'html_tag__h3',
-        '#tag' => 'h3',
-        );
-      switch ($config_change_type) {
-        case 'create':
-          $form[$config_change_type]['heading']['#value'] = format_plural(count($config_files), '@count new', '@count new');
-          break;
-
-        case 'change':
-          $form[$config_change_type]['heading']['#value'] = format_plural(count($config_files), '@count changed', '@count changed');
-          break;
-
-        case 'delete':
-          $form[$config_change_type]['heading']['#value'] = format_plural(count($config_files), '@count removed', '@count removed');
-          break;
-      }
-      $form[$config_change_type]['list'] = array(
-        '#theme' => 'table',
-        '#header' => array('Name', 'Operations'),
-      );
-
-      foreach ($config_files as $config_file) {
-        $links['view_diff'] = array(
-          'title' => t('View differences'),
-          'href' => 'admin/config/development/sync/diff/' . $config_file,
-          'attributes' => array(
-            'class' => array('use-ajax'),
-          ),
-        );
-        $form[$config_change_type]['list']['#rows'][] = array(
-          'name' => $config_file,
-          'operations' => array(
-            'data' => array(
-              '#type' => 'operations',
-              '#links' => $links,
-            ),
-          ),
-        );
-      }
-    }
     return $form;
   }