I love Bitcoin Payment Protocol (except for its reliance on the "old" system of CAs), but I am not sure what is the use case here.
Is it just for payments where both sides use Coinbase? That sounds ridiculous, but that's what I see on the picture. And I still don't get which side needs to use Coinbase.
By the way, Bitpay already uses BIP70 - if your mobile application supports it, you just scan the barcode and the URL is included.
It's for both sides. If you are paying a non-Coinbase merchant, and they support the payment protocol, you will see the merchant's name, address, and amount displayed. If you are paying a Coinbase merchant from a non-Coinbase wallet, you will see the address and amount correctly displayed.
If you are paying a Coinbase merchant from a Coinbase wallet, normally you wouldn't use this feature (since you can already log in directly and pay them).
> Is it just for payments where both sides use Coinbase? That sounds ridiculous, but that's what I see on the picture.
No it isn't. The user clicks "send with Bitcoin address", the same as they always have, in order to initiate this flow. Paying from Coinbase to Coinbase uses the other flow, usually.
Is it just for payments where both sides use Coinbase? That sounds ridiculous, but that's what I see on the picture. And I still don't get which side needs to use Coinbase.
By the way, Bitpay already uses BIP70 - if your mobile application supports it, you just scan the barcode and the URL is included.