GitLab

Changes:
* PaymentHandlerMediator, PaymentHandlerActivity returns different
messages for different errors.
* ServiceWorkerPaymentAppBridge combines similar methods into
onClosingPaymentAppWindow().
* Added two enums to PaymentEventResponseType in payment_app.mojom and
sorted all enums of the type:
 - PAYMENT_HANDLER_ACTIVITY_DIED
 - PAYMENT_HANDLER_FAIL_TO_LOAD_MAIN_FRAME

Bug: 1091957

Change-Id: Iab712ea3b72965ffd4e2bae6a1bd1c5e4776e441
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2469116Reviewed-by: Sahel Sharify <sahel@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Liquan (Max) Gu <maxlg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822793}