[WebProfilerBundle] Add a "previews tab in mailer profiler for HTML email

Author: lyrixx

DataCollector/MessageDataCollector.php

@@ -42,6 +42,14 @@ public function getEvents(): MessageEvents
         return $this->data['events'];
     }
 
+    /**
+     * @internal
+     */
+    public function base64Encode(string $data): string
+    {
+        return base64_encode($data);
+    }
+
     /**
      * {@inheritdoc}
      */