Stop chrome from prompting when running external URL handler?

Question

I've configured an external handler for telnet:// links following these instructions. It works great, but every time I click on a click chrome asks me:

Open xdg-open? http://<site i am browsing> wants to open this application

I would like telnet links to Just Work without the intervening prompt. How do I tell chrome to launch the external handler without prompting?

[NB: I'm running Chrome on Linux]

Answer 1

Solution in comment worked for me aswell. I'll post it.

---

Create following path and file:

sudo mkdir -p /etc/opt/chrome/policies/managed/
sudo touch /etc/opt/chrome/policies/managed/managed_policies.json

Open permissions for this file:

sudo chmod -R 775 /etc/opt/chrome/policies/managed

By default adding following content to this file should add the checkbox to remember your choice:

{
    "ExternalProtocolDialogShowAlwaysOpenCheckbox": true
}

This worked for all external website for me. For custom link (like telnet://* in the question), you may need to add those links to the whitelist:

{
    "ExternalProtocolDialogShowAlwaysOpenCheckbox": true,
    "URLWhitelist": [
        "telnet://*"
    ]
}