Based on this shiur from R. Sobolofsky, chocolate chip challah is no different from chocolate babka or other cake and thus has the bracha of mezonos.
If that is the case, one would only be able to make ha-motzei on such challah if he is koevia seudah on it. According to a review article at the OU
there are three ways in which one can be koveiah seudah on mezonos. 1) You eat an average person's full meal's worth of just that mezonos. 2) You eat what is enough for you personally to be satisfied for an entire meal. 3) You treat the mezonos as bread and eat enough of it along with other foods to be equivalent in amount to a regular meal with bread and other foods.
So the problem is: if you hold position 1) or 2), there might not be enough of the mezonos for you to fulfill the requirement (especially at a large dinner where everyone just gets the usual kazayis size piece of challah). So what should one do?