Hi,
Are you already working on this? (You marked as 'Available')
If not so, would you mind if I take this issue over?

I am not working on this. Feel free to take it.

I'll take this as per #4 comment.

Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/434828bc5ea0c5e62dafdd87045a65a8d61349e0

commit 434828bc5ea0c5e62dafdd87045a65a8d61349e0
Author: jinho.bang <jinho.bang@samsung.com>
Date: Mon Jun 27 21:42:31 2016

PaymentRequest: Implement PaymentDetailsModifier dictionary (in blink side).

The PaymentDetailsModifier allows details to modify the PaymentDetails based on
payment method identifier. It is used to add a discount or surcharge line item
indicating the reason for the different total amount, for example.

This CL is adding the dictionary, mojo interface and related tests but doesn't
include UI change to indicate total amount as per payment method identifier.

Related spec link:
  https://w3c.github.io/browser-payment-api/#paymentdetailsmodifier-dictionary

BUG= 618857 

Review-Url: https://codereview.chromium.org/2101463002
Cr-Commit-Position: refs/heads/master@{#402297}

[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/LayoutTests/payments/payment-request-interface.html
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/modules.gypi
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/payments/PaymentDetails.idl
[add] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/payments/PaymentDetailsModifier.idl
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/payments/PaymentRequestDetailsTest.cpp
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/payments/PaymentTestHelper.cpp
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/Source/modules/payments/PaymentTestHelper.h
[modify] https://crrev.com/434828bc5ea0c5e62dafdd87045a65a8d61349e0/third_party/WebKit/public/platform/modules/payments/payment_request.mojom

I will be taking care of the UI.

Android is ready to go. Need UI for desktop. I believe Anthony was going to look into it in the future.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/059d59a5bb73dcceb7d655c8e67b168642db2928

commit 059d59a5bb73dcceb7d655c8e67b168642db2928
Author: Anthony Vallee-Dubois <anthonyvd@chromium.org>
Date: Fri Jul 07 15:05:49 2017

[Web Payments] Implement modifier support

Bug:  618857 
Change-Id: I2c17940cd681874a8f0582f2066069f47744a955
Reviewed-on: https://chromium-review.googlesource.com/550401
Commit-Queue: Anthony Vallee-Dubois <anthonyvd@chromium.org>
Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#484926}
[add] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/modifiers_browsertest.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/order_summary_view_controller.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/payment_request_dialog_view_ids.h
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/payment_request_sheet_controller.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/payment_sheet_view_controller.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/profile_list_view_controller.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/shipping_option_view_controller.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/browser/ui/views/payments/view_stack.h
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/test/BUILD.gn
[add] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/test/data/payments/bobpay_and_basic_card_with_basic_card_modifiers.js
[add] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/chrome/test/data/payments/payment_request_bobpay_and_basic_card_with_basic_card_modifiers_test.html
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/components/payments/content/payment_request_spec.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/components/payments/content/payment_request_spec.h
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/components/payments/core/autofill_payment_instrument.cc
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/components/payments/core/autofill_payment_instrument.h
[modify] https://crrev.com/059d59a5bb73dcceb7d655c8e67b168642db2928/components/payments/core/payment_instrument.h

The desktop implementation is complete (% a couple minor issues with filtering tracked elsewhere).