[mmcwilliams]

I'm not sure about the chrome-extension protocol, but this API still seems to be present: https://developer.chrome.com/extensions/runtime#method-sendM...

[penagwin]

I just tested in chrome 77, and I could only do `chrome.runtime.sendMessage("clngdbkpkpeebahjckkjfobafhncgmne", {},{},console.log)` from within the Stylus extension page, not from an external page like hacker news.