[Pkg-chromium-maint] Bug#851927: This is still broken on 55.0.2883.75-6

[Jean-Francois Pirus]

The extensions are still disabled when starting chromium. Having to edit 
the startup script every time there is an update is not a valid solution.

This should either go back to the previous behaviour, or have a way of 
enabling the previous behaviour (ie: extensions that work) that is 
permanent across updates.