Payment App receiving customer details

Hi

I would like to discuss the potential for Payment Apps to receive customer
and purchase details provided by the merchant or collected by the browser.
This is related to the discussion in issue #13 (
https://github.com/w3c/webpayments-payment-apps-api/issues/13) and issue
#91 (https://github.com/w3c/webpayments-payment-apps-api/issues/91). Can we
put this on the agenda for next weeks meeting?

Use cases:
1. A user have multiple "accounts", e.g. private/business. Payment App can
identify this by email/phone
2. Shared computer/browser. Payment App can identify the user by email/phone
3. Payment App require customer or purchase details. Payment App do not
have to ask for the same information again / The merchant does not have to
provide the information in two places (payment method specific object)

*Suggested solution*

When a Payment App requests permission to handle payments it can optionally
request for customer and purchase details to be shared with the App. For
Payment Apps that have the users consent to share customer/purchase details
the browser will forward this information (when available) to the Payment
App when invoked.

The user will see something like this when permission is requested:
"Allow boopay.com to handle payments.
Your shipping address will be shared with boopay.com when making a payment"


Related to the discussion in #94 (
https://github.com/w3c/webpayments-payment-apps-api/issues/94) when
permission is asked for an optional "scope" can be provided.

Scopes:
* displayItems
* payer (covers all of the below)
* payer:email
* payer:phone
* payer:shipping

Example:
..requestPermission({scope: 'displayItems, payer:email'})

Regards

/frank