AFAICT from tons of references in the SFXGame/Online files mass effect 2 used it, so maybe it was the first to ship it?
EDIT: a lot of the older games instead used to rely on the FESL, or Theater (or Plasma at least in the case of BFBC2) protocol
EDIT2: that was only some kind of glue between backends, insofar as you can see it working (and crashing) with both the older gamespy titles and the new ones using the so-called Nucleus accounts. Blaze was probably the next step, cutting the old cruft and just integrating with their own new system (whose monicker, fun fact, was at a point even more important than Origin itself)