diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index dd68804389..9b04cf3b6e 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -505,7 +505,8 @@ function drupal_set_message($message = NULL, $type = 'status', $repeat = FALSE)
  */
 function drupal_get_messages($type = NULL, $clear_queue = TRUE) {
   /** @var \Drupal\Core\Messenger\MessengerInterface $messenger */
-  if (($messenger = \Drupal::hasService('messenger') ? \Drupal::service('messenger') : NULL) && $messages = $messenger->all()) {
+  if ((($messenger = \Drupal::hasService('messenger')) ? \Drupal::service('messenger') : NULL)
+    && $messages = $messenger->all()) {
     if ($type) {
       if ($clear_queue) {
         $messenger->deleteByType($type);
diff --git a/core/lib/Drupal/Core/Messenger/LegacyMessenger.php b/core/lib/Drupal/Core/Messenger/LegacyMessenger.php
index be46c44b5f..69c229286e 100644
--- a/core/lib/Drupal/Core/Messenger/LegacyMessenger.php
+++ b/core/lib/Drupal/Core/Messenger/LegacyMessenger.php
@@ -9,7 +9,7 @@
  * A legacy implementation of the messenger interface.
  *
  * @internal
- * @deprecated Deprecated as of Drupal 8.4.
+ * @deprecated Deprecated as of Drupal 8.5.x
  */
 class LegacyMessenger implements MessengerInterface {
 
@@ -17,7 +17,7 @@ class LegacyMessenger implements MessengerInterface {
    * {@inheritdoc}
    */
   public function addMessage($message, $type = self::TYPE_STATUS, $repeat = FALSE) {
-    _drupal_set_message($message, $type, $repeat);
+    $this->setMessage($message, $type, $repeat);
   }
 
   /**
@@ -45,106 +45,107 @@ public function addWarning($message, $repeat = FALSE) {
    * {@inheritdoc}
    */
   public function all() {
-    return _drupal_get_messages(NULL, FALSE);
+    return $this->getMessages(NULL, FALSE);
   }
 
   /**
    * {@inheritdoc}
    */
   public function messagesByType($type) {
-    return _drupal_get_messages($type, FALSE);
+    return $this->getMessages($type, FALSE);
   }
 
   /**
    * {@inheritdoc}
    */
   public function deleteAll() {
-    return _drupal_get_messages(NULL, TRUE);
+    return $this->getMessages(NULL, TRUE);
   }
 
   /**
    * {@inheritdoc}
    */
   public function deleteByType($type) {
-    return _drupal_get_messages($type, TRUE);
+    return $this->getMessages($type, TRUE);
   }
 
-}
+  /**
+   * @internal 
+   */
+  private function setMessage($message = NULL, $type = 'status', $repeat = FALSE) {
+    if (isset($message)) {
+      if (!isset($_SESSION['messages'][$type])) {
+        $_SESSION['messages'][$type] = [];
+      }
 
-/**
- * @internal
- */
-function _drupal_set_message($message = NULL, $type = 'status', $repeat = FALSE) {
-  if (isset($message)) {
-    if (!isset($_SESSION['messages'][$type])) {
-      $_SESSION['messages'][$type] = [];
-    }
+      // Convert strings which are safe to the simplest Markup objects.
+      if (!($message instanceof Markup) && $message instanceof MarkupInterface) {
+        $message = Markup::create((string) $message);
+      }
 
-    // Convert strings which are safe to the simplest Markup objects.
-    if (!($message instanceof Markup) && $message instanceof MarkupInterface) {
-      $message = Markup::create((string) $message);
-    }
+      // Do not use strict type checking so that equivalent string and
+      // MarkupInterface objects are detected.
+      if ($repeat || !in_array($message, $_SESSION['messages'][$type])) {
+        $_SESSION['messages'][$type][] = $message;
+      }
 
-    // Do not use strict type checking so that equivalent string and
-    // MarkupInterface objects are detected.
-    if ($repeat || !in_array($message, $_SESSION['messages'][$type])) {
-      $_SESSION['messages'][$type][] = $message;
+      // Mark this page as being uncacheable.
+      \Drupal::service('page_cache_kill_switch')->trigger();
     }
 
-    // Mark this page as being uncacheable.
-    \Drupal::service('page_cache_kill_switch')->trigger();
+    // Messages not set when DB connection fails.
+    return isset($_SESSION['messages']) ? $_SESSION['messages'] : NULL;
   }
 
-  // Messages not set when DB connection fails.
-  return isset($_SESSION['messages']) ? $_SESSION['messages'] : NULL;
-}
-
-/**
- * Returns all messages that have been set with drupal_set_message().
- *
- * @param string $type
- *   (optional) Limit the messages returned by type. Defaults to NULL, meaning
- *   all types. These values are supported:
- *   - NULL
- *   - 'status'
- *   - 'warning'
- *   - 'error'
- * @param bool $clear_queue
- *   (optional) If this is TRUE, the queue will be cleared of messages of the
- *   type specified in the $type parameter. Otherwise the queue will be left
- *   intact. Defaults to TRUE.
- *
- * @return array
- *   An associative, nested array of messages grouped by message type, with
- *   the top-level keys as the message type. The messages returned are
- *   limited to the type specified in the $type parameter, if any. If there
- *   are no messages of the specified type, an empty array is returned. See
- *   drupal_set_message() for the array structure of individual messages.
- *
- * @see drupal_set_message()
- * @see status-messages.html.twig
- *
- * @internal
- * @deprecated Deprecated as of Drupal 8.4.
- *   Use \Drupal::service('messenger')->getMessages() or
- *   \Drupal::service('messenger')->getMessagesByType() instead.
- */
-function _drupal_get_messages($type = NULL, $clear_queue = TRUE) {
-  if ($messages = _drupal_set_message()) {
-    if ($type) {
-      if ($clear_queue) {
-        unset($_SESSION['messages'][$type]);
-      }
-      if (isset($messages[$type])) {
-        return [$type => $messages[$type]];
+  /**
+   * Returns all messages that have been set with drupal_set_message().
+   *
+   * @param string $type
+   *   (optional) Limit the messages returned by type. Defaults to NULL, meaning
+   *   all types. These values are supported:
+   *   - NULL
+   *   - 'status'
+   *   - 'warning'
+   *   - 'error'
+   * @param bool $clear_queue
+   *   (optional) If this is TRUE, the queue will be cleared of messages of the
+   *   type specified in the $type parameter. Otherwise the queue will be left
+   *   intact. Defaults to TRUE.
+   *
+   * @return array
+   *   An associative, nested array of messages grouped by message type, with
+   *   the top-level keys as the message type. The messages returned are
+   *   limited to the type specified in the $type parameter, if any. If there
+   *   are no messages of the specified type, an empty array is returned. See
+   *   drupal_set_message() for the array structure of individual messages.
+   *
+   * @see drupal_set_message()
+   * @see status-messages.html.twig
+   *
+   * @internal
+   * @deprecated Deprecated as of Drupal 8.5.
+   *   Use \Drupal::service('messenger')->getMessages() or
+   *   \Drupal::service('messenger')->getMessagesByType() instead.
+   */
+  private function getMessages($type = NULL, $clear_queue = TRUE) {
+    if ($messages = $this->setMessage()) {
+      if ($type) {
+        if ($clear_queue) {
+          unset($_SESSION['messages'][$type]);
+        }
+        if (isset($messages[$type])) {
+          return [$type => $messages[$type]];
+        }
       }
-    }
-    else {
-      if ($clear_queue) {
-        unset($_SESSION['messages']);
+      else {
+        if ($clear_queue) {
+          unset($_SESSION['messages']);
+        }
+        return $messages;
       }
-      return $messages;
     }
+    return [];
   }
-  return [];
+
 }
+