Testing instructions for isSecurePaymentConfirmationAvailable API in Chrome

Howdy public-payments-wg@,

As I promised in the WPWG call earlier today, here are instructions on
testing the isSecurePaymentConfirmationAvailable
<https://w3c.github.io/secure-payment-confirmation/#sctn-secure-payment-confirmation-available-api>
API in Chrome.

1. Requires Chrome 135.0.7005.0 or higher, on any platform that supports
SPC (MacOS, Windows, Android). Chrome Canary should be at a sufficient
version currently.
2. Visit chrome://flags/#is-secure-payment-confirmation-available-api ,
enable the "isSecurePaymentConfirmationAvailable API" flag, and restart
your browser when prompted.
3. Now in JavaScript, there should be a static
'isSecurePaymentConfirmationAvailable' method on 'PaymentRequest', which
returns a promise<bool>.
4. You can test that it is working by writing your own JavaScript, or
visiting https://rsolomakhin.github.io/pr/spc/ - you should see
"PaymentRequest.isSecurePaymentConfirmationAvailable: {true, false}"

Please try this out on devices where you would/wouldn't expect SPC to be
available, and confirm that it works as you expect. Let us know if there
are any unexpected results!

As per the discussion, I will also be opening a github issue to discuss if
it's useful/feasible to have this method return an enum of reasons, rather
than just a true/false bool. I've not yet thought about the privacy angle,
so no promises!

I also promised instructions for BBKs - I will send those on Monday, as we
actually just identified a crash that we're fixing and then will need to
roll into Canary 😅

Thanks,
Stephen

-- 
smcgruer • he / him