Web Payment （在线支付/网上支付）

1. Payment Request API
   https://wicg.github.io/paymentrequest/specs/paymentrequest.html

2. Payment Request Architecture
   https://wicg.github.io/paymentrequest/specs/architecture.html#dfn-payment-method

3. Web Payments Use Cases 1.0
   https://www.w3.org/TR/2015/WD-web-payments-use-cases-20150416/

4. Web Payments Browser API 1.0
   https://wicg.github.io/web-payments-browser-api/