I've got good news and bad news for you.
First the bad news. You can't make it in 50 minutes. For US-US connections within Terminal 3 (what you're doing on AA ORD-YYZ-ORD) the MCT is 90 minutes.
The (really) good news is that according to the wiki at:
http://www.flyertalk.com/forum/ameri...d-tickets.html
When you're flying on 2 OneWorld tickets (including 2 AA tickets) you'll be protected as if you're flying on 1 ticket, so you can relax about a delay screwing up your whole itinerary.