Patrick Griffis authored Dec 17, 2018 and Michael Catanzaro committed Jan 31, 2019

When the WebKitGTK sandbox is enabled the web processes
will not have access to DConf so these will not work.

They do however have read access to our private directories
so we can simply write a keyfile there and load them from the
web extensions.

The keyfile is simply kept in sync with the host DConf so all
previous usage continues to work as expected.