I had almost the identical thing happen Monday morning from SEA to SFO also on a UA A319. During approach into SFO, before doing final left turn over the south bay, the lights went out and engines to full throttle for a moment. We continued way further south than normal before turning left and back up to land 10-15 minutes later.
Upon landing the captain said there was an electrical failure. When deplaning a mechanic was standing on the jet bridge muttering something about another broken plane today.
I didn't notice whether an engine went out as well. I don't think so.
Anyone out there think they know what's up?