If the requestPayerName flag was set to true in the PaymentOptions passed to the PaymentRequest constructor, then UA should collect and return the payer's name as part of the payment request. For example, this would be set to true to allow merchant to make a booking in the payer's name. This option has been behind a flag on mobile since Chrome 55. On desktop, it's shipping in Chrome 60 with the rest of Payment Request API.
Docs: https://developer.mozilla.org/en-US/docs/Web/API/PaymentRequest/PaymentRequest