Air carrier Captain reported on descent experiencing left pack failure resulting in no air conditioning available and flight receiving priority handing to the airport.

Narrative

Approximately 12;000 feet on the ZZZZZ STAR. The First Officer (FO) and I smelled a strong electrical burning smell. We complied with Memory items for Smoke/Fire/Fumes procedure. Tried to determine where the smell was coming from. There were no faults or messages on the EICAS. The First Officer suggested unplugging our IPads; we both unplugged and there was no change. The FO called the Flight Attendants and they too could smell the odor; but only near the cockpit door. By now we noticed the pack temperature rising and this was the description given by a previous crew when the right pack had failed earlier in the week; and was currently on an MEL. The FO asked for a lower altitude below 10;000 feet. We were almost to ZZZZZ intersection; so ZZZ Approach gave us 3;000 feet and headings for the ILS to XXR. We continued the approach to a normal landing with the masks on. At approximately 200 feet the left pack failed from an overheat condition. The FO complied with the pack overheat checklist after landing once we were clear of the runway. We asked for priority handling to the gate since the cabin temperature was increasing due to no air conditioning being available. The FO made an announcement to the passengers that we were trying to get to the gate as soon as possible since we knew it was getting warm in the cabin. We wrote up the Pack Overheat and the Flight Deck oxygen masks had been used requiring Oxygen level servicing.