Microsoft’s purchase of video game maker Activision Blizzard has won final approval from Britain’s competition watchdog. The move Friday reversed its earlier decision to block the $69 billion deal and removing a last obstacle for one of the largest tech transactions in history. The Competition and Markets Authority’s blessing was expected after it gave preliminary approval last month to a revamped Microsoft proposal meant to address concerns that the deal would harm competition and hurt gamers. It signals certain victory in the Xbox maker’s quest to acquire Activision, maker of the popular Call of Duty game franchise. The companies had agreed to extend an original mid-July deadline to Oct. 18 to overcome the British regulator’s objections.