GitLab

Uses the id property of the PaymentDetails provided to PaymentRequest's
constructor or generate a UUID to uniquely identify the PaymentRequest
in order to allow multiple PaymentRequest objects to coexist.

BUG=602666

Change-Id: I420e9fba0314cc9683b274fea71e0118b31e572e
Reviewed-on: https://chromium-review.googlesource.com/565056
Commit-Queue: mahmadi <mahmadi@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486265}