The Facebook Messenger Customer Chat Plugin module enables you to add the Facebook Messenger Customer Chat Plugin to your Drupal site. The module doesn’t require user permissions on the admin page.
www.drupal.org/project/fb_messenger_customer_chat_plugin
www.drupal.org/project/fb_messenger_customer_chat_plugin/releases/7.x-1.1
www.drupal.org/user/102818
www.drupal.org/user/36762
www.drupal.org/user/854220