Issue #1963988 by joelpittet, Gaelan, chrisjlee: Convert theme_views_ui_view_preview_section() to Twig.

core/modules/views_ui/templates/views-ui-view-preview-section.html.twig

@@ -0,0 +1,20 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a views UI preview section.
+ *
+ * Available variables:
+ * - title: The human readable section title.
+ * - links: A list of contextual links.
+ * - content: The content for this section preview.
+ *
+ * @see template_preprocess_views_ui_view_preview_section()
+ *
+ * @ingroup themeable
+ */
+#}
+<h1 class="section-title">{{ title }}</h1>
+{% if links %}
+  <div class="contextual">{{ links }}</div>
+{% endif %}
+<div class="preview-section">{{ content }}</div>

core/modules/views_ui/views_ui.module

@@ -176,6 +176,7 @@ function views_ui_theme() {
     'views_ui_view_preview_section' => array(
       'variables' => array('view' => NULL, 'section' => NULL, 'content' => NULL, 'links' => ''),
       'file' => 'views_ui.theme.inc',
+      'template' => 'views-ui-view-preview-section',
     ),
 
     // Generic container wrapper, to use instead of theme_container when an id

core/modules/views_ui/views_ui.theme.inc

@@ -389,7 +389,14 @@ function theme_views_ui_style_plugin_table($variables) {
 }
 
 /**
- * Theme preprocess for theme_views_ui_view_preview_section().
+ * Prepares variables for views UI view preview section templates.
+ *
+ * Default template: views-ui-view-preview-section.html.twig.
+ *
+ * @param array $variables
+ *   An associative array containing:
+ *   - view: The view object.
+ *   - section: The section name of a View (e.g. title, rows or pager).
  */
 function template_preprocess_views_ui_view_preview_section(&$vars) {
   switch ($vars['section']) {
@@ -439,8 +446,6 @@ function template_preprocess_views_ui_view_preview_section(&$vars) {
 
   if (isset($links)) {
     $build = array(
-      '#prefix' => '<div class="contextual">',
-      '#suffix' => '</div>',
       '#theme' => 'links__contextual',
       '#links' => $links,
       '#attributes' => array('class' => array('contextual-links')),
@@ -448,16 +453,7 @@ function template_preprocess_views_ui_view_preview_section(&$vars) {
         'library' => array(array('contextual', 'drupal.contextual-links')),
       ),
     );
-    $vars['links'] = drupal_render($build);
+    $vars['links'] = $build;
   }
   $vars['theme_hook_suggestions'][] = 'views_ui_view_preview_section__' . $vars['section'];
 }
-
-/**
- * Returns the HTML for a section of a View being previewed within the Views UI.
- */
-function theme_views_ui_view_preview_section($vars) {
-  return '<h1 class="section-title">' . $vars['title'] . '</h1>'
-  . $vars['links']
-  . '<div class="preview-section">'. drupal_render($vars['content']) . '</div>';
-}