I would like users to be able to disable the builtin extensions at runtime. This is driven mainly by a few recent crashes around the Google Hangouts extension:

https://bugreports.qt.io/browse/QTBUG-113369
https://bugreports.qt.io/browse/QTBUG-118157
https://bugreports.qt.io/browse/QTBUG-99119

We've been quite helpless to workaround those issues without getting users new webengine builds as nothing relating to extensions seems to be exposed in the webengine API.

As an aside, I don't fully understand why this extension was introduced in https://bugreports.qt.io/browse/QTBUG-85731. Can we not convince hangouts to fall back to standard webrtc APIs? Does hangouts not work with firefox?