Microsoft’s Windows Phone operating system has struggled to make gains against Google and Apple. But it may soon get a shot in the arm from an old partner and rival: Sony. Sony, whose mobile unit has exclusively made smartphones powered by Google’s Android software for nearly four years, has considered launching a Windows phone as soon as mid-2014, according to a person who was involved in the talks and a person briefed about the device. The talks come as Microsoft is making new moves to attract other partners such as China-based ZTE. It has boosted incentives for potential Windows Phone handset makers, including slashing the software licensing fees it would charge them.