Function serve_shared_until_idle 

pub fn serve_shared_until_idle()

Blocks while other Browser processes still use a Chromium host this process runs, then stops serving them; a host none of this process’s engines still uses shuts down before this returns.

Call it once the UI event loop has exited and the app has dropped its engines: the process that started a profile’s host must outlive every process browsing through it. Returns at once when nothing is shared.