I can assure you that it wasn't related just to rebooting as this has been something that's been bugging me for months. I had previously rebooted earlier in the day because of this exact same issue (a runaway WindowServer process), before I saw this article. I also did a fresh reboot before following these instructions too as a sort of "control".
The change only happened for me after removing Chrome as well as the launch agent for keystone.
The change only happened for me after removing Chrome as well as the launch agent for keystone.