diff --git a/core/authorize.php b/core/authorize.php
index 22bede6..231ad8d 100644
--- a/core/authorize.php
+++ b/core/authorize.php
@@ -149,7 +149,7 @@ function authorize_access_allowed() {
 
 if (!empty($output)) {
   $response->headers->set('Content-Type', 'text/html; charset=utf-8');
-  $response->setContent(\Drupal::service('bare_html_page_renderer')->renderMaintenancePage($output, $page_title, array(
+  $response->setContent(\Drupal::service('bare_html_page_renderer')->renderBarePage(['#markup' => $output], $page_title, 'maintenance_page', array(
     '#show_messages' => $show_messages,
   )));
   $response->send();
diff --git a/core/includes/batch.inc b/core/includes/batch.inc
index 59e1529..088889d 100644
--- a/core/includes/batch.inc
+++ b/core/includes/batch.inc
@@ -135,7 +135,7 @@ function _batch_progress_page() {
     // additional HTML output by PHP shows up inside the page rather than below
     // it. While this causes invalid HTML, the same would be true if we didn't,
     // as content is not allowed to appear after </html> anyway.
-    $fallback = \Drupal::service('bare_html_page_renderer')->renderMaintenancePage($fallback, $current_set['title'], array(
+    $fallback = \Drupal::service('bare_html_page_renderer')->renderBarePage(['#markup' => $fallback], $current_set['title'], 'maintenance_page', array(
       '#show_messages' => FALSE,
     ));
     list($fallback) = explode('<!--partial-->', $fallback);
diff --git a/core/includes/errors.inc b/core/includes/errors.inc
index a3c3564..fbdb68c 100644
--- a/core/includes/errors.inc
+++ b/core/includes/errors.inc
@@ -235,7 +235,7 @@ function _drupal_log_error($error, $fatal = FALSE) {
         install_display_output($output, $GLOBALS['install_state']);
       }
       else {
-        $output = \Drupal::service('bare_html_page_renderer')->renderMaintenancePage($message, 'Error');
+        $output = \Drupal::service('bare_html_page_renderer')->renderBarePage(['#markup' => $message], 'Error', 'maintenance_page');
       }
 
       $response = new Response($output, 500);
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 0899bec..4673745 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -933,7 +933,7 @@ function install_display_output($output, $install_state) {
     'ETag' => '"' . REQUEST_TIME . '"',
   );
   $response->headers->add($default_headers);
-  $response->setContent(\Drupal::service('bare_html_page_renderer')->renderInstallPage($output, $output['#title'], $regions));
+  $response->setContent(\Drupal::service('bare_html_page_renderer')->renderBarePage($output, $output['#title'], 'install_page', $regions));
   $response->send();
   exit;
 }
diff --git a/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionSubscriber.php
index 88fac22..c8bc8b1 100644
--- a/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionSubscriber.php
@@ -133,7 +133,7 @@ protected function onHtml(GetResponseForExceptionEvent $event) {
     }
 
     $content = $this->t('The website has encountered an error. Please try again later.');
-    $output = $this->bareHtmlPageRenderer->renderMaintenancePage($content, $this->t('Error'));
+    $output = $this->bareHtmlPageRenderer->renderBarePage(['#markup' => $content], $this->t('Error'), 'maintenance_page');
     $response = new Response($output);
 
     if ($exception instanceof HttpExceptionInterface) {
diff --git a/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
index 164dec0..bdd05c7 100644
--- a/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
@@ -105,7 +105,7 @@ public function onKernelRequestMaintenance(GetResponseEvent $event) {
         $content = Xss::filterAdmin(String::format($this->config->get('system.maintenance')->get('message'), array(
           '@site' => $this->config->get('system.site')->get('name'),
         )));
-        $output = $this->bareHtmlPageRenderer->renderMaintenancePage($content, $this->t('Site under maintenance'));
+        $output = $this->bareHtmlPageRenderer->renderBarePage(['#markup' => $content], $this->t('Site under maintenance'), 'maintenance_page');
         $response = new Response($output, 503);
         $event->setResponse($response);
       }
diff --git a/core/lib/Drupal/Core/Render/BareHtmlPageRenderer.php b/core/lib/Drupal/Core/Render/BareHtmlPageRenderer.php
index d744e19..ca7aa18 100644
--- a/core/lib/Drupal/Core/Render/BareHtmlPageRenderer.php
+++ b/core/lib/Drupal/Core/Render/BareHtmlPageRenderer.php
@@ -8,56 +8,19 @@
 namespace Drupal\Core\Render;
 
 /**
- * Default bare HTML page renderer
+ * Default bare HTML page renderer.
  */
 class BareHtmlPageRenderer implements BareHtmlPageRendererInterface {
 
   /**
    * {@inheritdoc}
    */
-  public function renderMaintenancePage($content, $title, array $page_additions = []) {
-    if (!is_array($content)) {
-      $content = ['#markup' => $content];
-    }
+  public function renderBarePage(array $content, $title, $page_theme_property, array $page_additions = []) {
     $attributes = [
       'class' => [
-        'maintenance-page',
+        str_replace('_', '-', $page_theme_property),
       ],
     ];
-    return $this->renderBarePage($content, $title, $page_additions, $attributes, 'maintenance_page');
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function renderInstallPage($content, $title, array $page_additions = []) {
-    $attributes = [
-      'class' => [
-        'install-page',
-      ],
-    ];
-    return $this->renderBarePage($content, $title, $page_additions, $attributes, 'install_page');
-  }
-
-  /**
-   * Renders a bare page.
-   *
-   * @param string|array $content
-   *   The main content to render in the 'content' region.
-   * @param string $title
-   *   The title for this maintenance page.
-   * @param array $page_additions
-   *   Additional regions to add to the page. May also be used to pass the
-   *   #show_messages property for #type 'page'.
-   * @param array $attributes
-   *   Attributes to set on #type 'html'.
-   * @param string $page_theme_property
-   *   The #theme property to set on #type 'page'.
-   *
-   * @return string
-   *   The rendered HTML page.
-   */
-  protected function renderBarePage(array $content, $title, array $page_additions, array $attributes, $page_theme_property) {
     $html = [
       '#type' => 'html',
       '#attributes' => $attributes,
diff --git a/core/lib/Drupal/Core/Render/BareHtmlPageRendererInterface.php b/core/lib/Drupal/Core/Render/BareHtmlPageRendererInterface.php
index 7450199..e8b2c5e 100644
--- a/core/lib/Drupal/Core/Render/BareHtmlPageRendererInterface.php
+++ b/core/lib/Drupal/Core/Render/BareHtmlPageRendererInterface.php
@@ -45,12 +45,14 @@
 interface BareHtmlPageRendererInterface {
 
   /**
-   * Renders a "maintenance" page, styled as such.
+   * Renders a bare page.
    *
-   * @param string|array $content
+   * @param array $content
    *   The main content to render in the 'content' region.
    * @param string $title
    *   The title for this maintenance page.
+   * @param string $page_theme_property
+   *   The #theme property to set on #type 'page'.
    * @param array $page_additions
    *   Additional regions to add to the page. May also be used to pass the
    *   #show_messages property for #type 'page'.
@@ -58,22 +60,6 @@
    * @return string
    *   The rendered HTML page.
    */
-  public function renderMaintenancePage($content, $title, array $page_additions = []);
-
-  /**
-   * Renders an "install" page, styled as such.
-   *
-   * @param string|array $content
-   *   The main content to render in the 'content' region.
-   * @param string $title
-   *   The title for this maintenance page.
-   * @param array $page_additions
-   *   Additional regions to add to the page. May also be used to pass the
-   *   #show_messages property for #type 'page'.
-   *
-   * @return string
-   *   The rendered HTML page.
-   */
-  public function renderInstallPage($content, $title, array $page_additions = []);
+  public function renderBarePage(array $content, $title, $page_theme_property, array $page_additions = []);
 
 }
diff --git a/core/modules/system/src/Controller/DbUpdateController.php b/core/modules/system/src/Controller/DbUpdateController.php
index cfd31dd..c3c25fa 100644
--- a/core/modules/system/src/Controller/DbUpdateController.php
+++ b/core/modules/system/src/Controller/DbUpdateController.php
@@ -199,7 +199,7 @@ public function handle($op, Request $request) {
     }
     $title = isset($output['#title']) ? $output['#title'] : $this->t('Drupal database update');
 
-    return new Response($this->bareHtmlPageRenderer->renderMaintenancePage($output, $title, $regions));
+    return new Response($this->bareHtmlPageRenderer->renderBarePage($output, $title, 'maintenance_page', $regions));
   }
 
   /**