The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b07da295cd5b096d560ba5ab84524bee321b5c54

commit b07da295cd5b096d560ba5ab84524bee321b5c54
Author: Rouslan Solomakhin <rouslan@chromium.org>
Date: Fri Nov 17 01:52:55 2017

[Payments] More verbose 'payment method not supported' message.

Before this patch, PaymentRequest.show() could reject with "Payment
method not supported" message, which did not clarify which payment
methods were not supported. This could be debugging confusing in a large
production environment, where multiple PaymentRequest instances with
different payment method names are created.

This patch stores the set of payment method names for each instance of
PaymentRequest and prints them out in the error message, if none of them
are supported.

After this patch, PaymentRequest.show() can reject with error message
"Payment method 'xyz' is not supported". (Plurals are handled
correctly.)

Bug:  785992 
Change-Id: I976b11b84f788ea98b4e413ca983edd8f792052d
Reviewed-on: https://chromium-review.googlesource.com/775045
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Rouslan Solomakhin <rouslan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517243}
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestFieldTrialTest.java
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestJourneyLoggerTest.java
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestMetricsTest.java
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestModifierTest.java
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestPaymentAppTest.java
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestServiceWorkerPaymentAppTest.java
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/third_party/WebKit/Source/modules/payments/PaymentRequest.cpp
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/third_party/WebKit/Source/modules/payments/PaymentRequest.h
[modify] https://crrev.com/b07da295cd5b096d560ba5ab84524bee321b5c54/third_party/WebKit/Source/modules/payments/PaymentRequestTest.cpp