Ugh...yeah. Been there done that. Makes you feel terrible right?! I always fed my labs Purina & Pedigree simply because I didn't know any different. Anyway, I agree ZiwiPeak is a great option. A bit pricey...probably would last your two Chi's 3 weeks for a 2.2lb bag ($27ish in our area). But there are some better kibbles out there as well if the ZiwiPeak is too steep. Taste of the Wild, Acana, Fromm, Orijen....all are great options. There is also Honest Kitchen which is a dehydrated raw but has more fruits & veggies compared to ZiwiPeak (which has none). Their Keen is pretty reasonable price wise. Has a grain in it (organic oats) but I'd probably go with this before a kibble myself.
Anyway, I'm very happy you researched enough to find out the truth! Pet food can contain some very scary things indeed. Good luck in your search to find a better food!