Tech giants Tencent (NASDAQOTH: TCEHY) and Baidu (NASDAQ: BIDU) are currently engaged in an ongoing O2O (online-to-offline) ecosystem war in China. Tencent is turning WeChat — the most popular messaging app in China — into an all-in-one platform for making payments, hailing cabs, playing games, ordering food, and making online purchases. That social-centric expansion forced Baidu, which owns the biggest search engine in China, to add similar services to its mobile app.