Comment 6 for bug 1423414

I'm having this problem on many machines. First time I've had time to work through it.. so, from a fresh install,

apt-get install xserver-xorg-lts-utopic
apt-get autoremove --purge

It's at this point that I can't install unity-control-center without downgrading to xserver-xorg. At least one problem package at this point is libcogl15 (pulled in by indicator-bluetooth, possibly others) which depends on libegl1-mesa-drivers.

This system has libegl1-mesa-lts-utopic, but it doesn't have any version of the drivers package.

apt-get install libegl1-mesa-drivers-lts-utopic
installs three packages

apt-get install unity-control-center
Installs unity control center without downgrading xserver-xorg.