diff --git a/core/modules/search/search.api.php b/core/modules/search/search.api.php
index 3f30a4a..2c49bc5 100644
--- a/core/modules/search/search.api.php
+++ b/core/modules/search/search.api.php
@@ -47,6 +47,43 @@ function hook_search_info() {
 }
 
 /**
+ * Provide search query conditions.
+ *
+ * Callback for hook_search_info().
+ *
+ * This callback is invoked by search_view() to get an array of additional
+ * search conditions to pass to search_data(). For example, a search module
+ * may get additional keywords, filters, or modifiers for the search from
+ * the query string.
+ *
+ * This example pulls additional search keywords out of the $_REQUEST variable,
+ * (i.e. from the query string of the request). The conditions may also be
+ * generated internally - for example based on a module's settings.
+ *
+ * @param $keys
+ *   The search keywords string.
+ *
+ * @return
+ *   An array of additional conditions, such as filters.
+ *
+ * @ingroup search
+ */
+function callback_search_conditions($keys) {
+  $conditions = array();
+
+  if (!empty($_REQUEST['keys'])) {
+    $conditions['keys'] = $_REQUEST['keys'];
+  }
+  if (!empty($_REQUEST['sample_search_keys'])) {
+    $conditions['sample_search_keys'] = $_REQUEST['sample_search_keys'];
+  }
+  if ($force_keys = config('sample_search.settings')->get('force_keywords')) {
+    $conditions['sample_search_force_keywords'] = $force_keys;
+  }
+  return $conditions;
+}
+
+/**
  * Define access to a custom search routine.
  *
  * This hook allows a module to define permissions for a search tab.
@@ -359,42 +396,3 @@ function hook_update_index() {
 /**
  * @} End of "addtogroup hooks".
  */
-
-/**
- * Provide search query conditions.
- *
- * Callback for hook_search_info().
- *
- * This callback is invoked by search_view() to get an array of additional
- * search conditions to pass to search_data(). For example, a search module
- * may get additional keywords, filters, or modifiers for the search from
- * the query string.
- *
- * This example pulls additional search keywords out of the $_REQUEST variable,
- * (i.e. from the query string of the request). The conditions may also be
- * generated internally - for example based on a module's settings.
- *
- * @param $keys
- *   The search keywords string.
- *
- * @return
- *   An array of additional conditions, such as filters.
- *
- * @ingroup callbacks
- * @ingroup search
- */
-function callback_search_conditions($keys) {
-  $conditions = array();
-
-  if (!empty($_REQUEST['keys'])) {
-    $conditions['keys'] = $_REQUEST['keys'];
-  }
-  if (!empty($_REQUEST['sample_search_keys'])) {
-    $conditions['sample_search_keys'] = $_REQUEST['sample_search_keys'];
-  }
-  if ($force_keys = config('sample_search.settings')->get('force_keywords')) {
-    $conditions['sample_search_force_keywords'] = $force_keys;
-  }
-  return $conditions;
-}
-
diff --git a/core/modules/views/templates/views-view-field.tpl.php b/core/modules/views/templates/views-view-field.tpl.php
deleted file mode 100644
index 91d92ee..0000000
--- a/core/modules/views/templates/views-view-field.tpl.php
+++ /dev/null
@@ -1,25 +0,0 @@
-<?php
-
-/**
- * @file
- * This template is used to print a single field in a view.
- *
- * It is not actually used in default Views, as this is registered as a theme
- * function which has better performance. For single overrides, the template is
- * perfectly okay.
- *
- * Variables available:
- * - $view: The view object
- * - $field: The field handler object that can process the input
- * - $row: The raw SQL result that can be used
- * - $output: The processed output that will normally be used.
- *
- * When fetching output from the $row, this construct should be used:
- * $data = $row->{$field->field_alias}
- *
- * The above will guarantee that you'll always get the correct data,
- * regardless of any changes in the aliasing that might happen if
- * the view is modified.
- */
-?>
-<?php print $output; ?>
diff --git a/core/modules/views/templates/views-view-fields.html.twig b/core/modules/views/templates/views-view-fields.html.twig
new file mode 100644
index 0000000..38525c7
--- /dev/null
+++ b/core/modules/views/templates/views-view-fields.html.twig
@@ -0,0 +1,42 @@
+{#
+/**
+ * @file
+ * Default view template to display all the fields in a row.
+ *
+ * Available variables:
+ * - view: The view in use.
+ * - fields: A list of fields, each one contains:
+ *   - content: The output of the field.
+ *   - raw: The raw data for the field, if it exists. This is NOT output safe.
+ *   - class: The safe class ID to use.
+ *   - handler: The Views field handler controlling this field.
+ *   - inline: Whether or not the field should be inline.
+ *   - inline_html: Either div or span based on the 'inline' flag.
+ *   - wrapper_prefix: A complete wrapper containing the inline_html to use.
+ *   - wrapper_suffix: The closing tag for the wrapper.
+ *   - separator: An optional separator that may appear before a field.
+ *   - label: The field's label text.
+ *   - label_html: The full HTML of the label to use including configured
+ *     element type.
+ * - row: The raw result from the query, with all data it fetched.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_views_view_fields()
+ *
+ * @ingroup themeable
+ */
+#}
+<!--
+THIS FILE IS NOT USED AND IS HERE AS A STARTING POINT FOR CUSTOMIZATION ONLY.
+See http://api.drupal.org/api/function/theme_views_view_fields/8 for details.
+After copying this file to your theme's folder and customizing it, remove this
+HTML comment.
+-->
+{% for field in fields %}
+  {{ field.separator }}
+
+  {{ field.wrapper_prefix }}
+    {{ field.label_html }}
+    {{ field.content }}
+  {{ field.wrapper_suffix }}
+{% endfor %}
diff --git a/core/modules/views/templates/views-view-fields.tpl.php b/core/modules/views/templates/views-view-fields.tpl.php
deleted file mode 100644
index ae3a4c6..0000000
--- a/core/modules/views/templates/views-view-fields.tpl.php
+++ /dev/null
@@ -1,36 +0,0 @@
-<?php
-
-/**
- * @file
- * Default simple view template to all the fields as a row.
- *
- * - $view: The view in use.
- * - $fields: an array of $field objects. Each one contains:
- *   - $field->content: The output of the field.
- *   - $field->raw: The raw data for the field, if it exists. This is NOT output safe.
- *   - $field->class: The safe class id to use.
- *   - $field->handler: The Views field handler object controlling this field. Do not use
- *     var_export to dump this object, as it can't handle the recursion.
- *   - $field->inline: Whether or not the field should be inline.
- *   - $field->inline_html: either div or span based on the above flag.
- *   - $field->wrapper_prefix: A complete wrapper containing the inline_html to use.
- *   - $field->wrapper_suffix: The closing tag for the wrapper.
- *   - $field->separator: an optional separator that may appear before a field.
- *   - $field->label: The wrap label text to use.
- *   - $field->label_html: The full HTML of the label to use including
- *     configured element type.
- * - $row: The raw result object from the query, with all data it fetched.
- *
- * @ingroup views_templates
- */
-?>
-<?php foreach ($fields as $id => $field): ?>
-  <?php if (!empty($field->separator)): ?>
-    <?php print $field->separator; ?>
-  <?php endif; ?>
-
-  <?php print $field->wrapper_prefix; ?>
-    <?php print $field->label_html; ?>
-    <?php print $field->content; ?>
-  <?php print $field->wrapper_suffix; ?>
-<?php endforeach; ?>
diff --git a/core/modules/views/views.theme.inc b/core/modules/views/views.theme.inc
index e987ffd..55af044 100644
--- a/core/modules/views/views.theme.inc
+++ b/core/modules/views/views.theme.inc
@@ -175,7 +175,23 @@ function template_preprocess_views_view(&$vars) {
 }
 
 /**
- * Preprocess theme function to print a single record from a row, with fields
+ * Prepares variables for views fields templates.
+ *
+ * Default template: views-view-fields.html.twig.
+ *
+ * @param array $vars
+ *   An associative array containing:
+ *   - view: The view object.
+ *   - options: An array of options. Each option contains:
+ *     - inline: An array that contains the fields that are to be
+ *       displayed inline.
+ *     - default_field_elements: If default field wrapper
+ *       elements are to be provided.
+ *     - hide_empty: Whether the field is to be hidden if empty.
+ *     - element_default_classes: If the default classes are to be added.
+ *     - separator: A string to be placed between inline fields to keep them
+ *       visually distinct.
+ *    - row: An array containing information about the current row.
  */
 function template_preprocess_views_view_fields(&$vars) {
   $view = $vars['view'];
@@ -296,6 +312,38 @@ function template_preprocess_views_view_fields(&$vars) {
 }
 
 /**
+ * Returns HTML for multiple views fields.
+ *
+ * @param $variables
+  *   An associative array containing:
+  *   - separator: A string that separates the fields.
+  *   - wrapper_suffix: A string added to the beginning of the fields.
+  *   - label_html: An HTML string that labels the fields.
+  *   - content: The fields.
+  *   - wrapper_suffix: A string added to the end of the fields.
+  *
+  * @see template_preprocess_views_view_fields()
+ */
+function theme_views_view_fields($vars) {
+  $fields = $vars['fields'];
+  $output = '';
+
+  foreach ($fields as $id => $field) {
+    if (!empty($field->separator)) {
+      $output .= $field->separator;
+    }
+
+    $output .= $field->wrapper_prefix;
+    $output .= $field->label_html;
+    $output .= $field->content;
+
+    $output .= $field->wrapper_suffix;
+  }
+
+  return $output;
+}
+
+/**
  * Process a single grouping within a view.
  */
 function template_preprocess_views_view_grouping(&$vars) {