A platform for testing Service Worker based Payment Apps

Happy new year everyone!

In response to the increased interest in implementing Payment Apps, I've
spent some time (together with Rouslan and Jinho) implementing support for
the Payment App API in Chromium. There's still a fair amount of work left,
but we've progressed far enough that I've been able to build a prototype
browser that can be used by implementors to do some preliminary testing of
their Payment Apps.

This prototype browser comes in the form of an Android APK file. It can be
downloaded from this page
<https://github.com/tommythorsen/webpayments-demo/blob/gh-pages/clients/README.md>.
There are some instructions on that page that will hopefully get you up and
running. If you experience problems, let me know.

The current version of the prototype browser supports installing a payment
app, and invoking it from the payment request dialog. It does not yet
support passing data back from the payment app to the merchant, but I'm
working on this. As we progress further, and implement more parts of the
specification, I will publish new versions of the APK.

Hope this can be of help to you :)

Best regards,
Tommy