Help with the new proc system

So with the implementation of QAston proc system on master I got completely lost on how to do some stuff.

Currently on warrior fury spec, when you use any kind of offensive ability enrage is triggered, but it should be triggered via bloodthirst critical strikes only. Now before the implementation of the new proc system I would handle this in Unit.cpp in HandleProcTriggerSpell, but this method was removed with the implementation of the QAston procsystem.

Now I’m asking what is its replacement or is there some alternative way of doing this stuff.