I have not been able to find any concrete information. There are various allusions to ChromeOS being configured in some way by default to to like connections to localhost, e.g.
You might try loading the autoload URL from the console log directly in a URL bar, seeing if there are any relevant settings (e.g. maybe something mentioned in that SO post above), or (if possible?) try other browsers on the Chromebook. Unfortunately I do not have access to any Chromebook to experiment.