Snapchat and Kik, the messaging services, use bar codes that look like drunken checkerboards to connect people and share information with a snap of their smartphone cameras. Facebook is working on adding the ability to hail rides and make payments within its Messenger app.
Facebook and Twitter have begun live-streaming video.
All of these developments have something in common: The technology was first popularised in China.
WeChat and Alipay, two Chinese apps, have long used the bar-codelike symbols - called QR codes - to let people pay.....