[Merge M-53] Enable closing while processing payment.

[Merge M-53] Enable closing while processing payment.

This patch allows closing PaymentRequest UI via the [x] button while
waiting for merchant to process the payment. This is accomplished by
switching off the "is processing pay clicked" flag when
showProcessingMessage() has been called. PaymentRequestImpl calls
showProcessingMessage() when payment app has closed and its info has
been sent to the merchant website.

BUG=637366
Review-Url: https://codereview.chromium.org/2247493002
Cr-Commit-Position: refs/heads/master@{#411881}
(cherry picked from commit 4d72ec4ded66ff9ad99497f5895433bccd179716)

Committed: https://chromium.googlesource.com/chromium/src/+/1a1d153e4ff3c681fb72a4290c575a52bdb6d2e9

[please use gerrit instead, 2016-08-19 16:59:45]

Description was changed from

==========
[Merge M-53] Enable closing while processing payment.

This patch allows closing PaymentRequest UI via the [x] button while
waiting for merchant to process the payment. This is accomplished by
switching off the "is processing pay clicked" flag when
showProcessingMessage() has been called. PaymentRequestImpl calls
showProcessingMessage() when payment app has closed and its info has
been sent to the merchant website.

BUG=637366

Review-Url: https://codereview.chromium.org/2247493002
Cr-Commit-Position: refs/heads/master@{#411881}
(cherry picked from commit 4d72ec4ded66ff9ad99497f5895433bccd179716)
==========

to

==========
[Merge M-53] Enable closing while processing payment.

This patch allows closing PaymentRequest UI via the [x] button while
waiting for merchant to process the payment. This is accomplished by
switching off the "is processing pay clicked" flag when
showProcessingMessage() has been called. PaymentRequestImpl calls
showProcessingMessage() when payment app has closed and its info has
been sent to the merchant website.

BUG=637366

Review-Url: https://codereview.chromium.org/2247493002
Cr-Commit-Position: refs/heads/master@{#411881}
(cherry picked from commit 4d72ec4ded66ff9ad99497f5895433bccd179716)

Committed:
https://chromium.googlesource.com/chromium/src/+/1a1d153e4ff3c681fb72a4290c57...
==========

[please use gerrit instead, 2016-08-19 16:59:46]

Committed patchset #1 (id:1) manually as
1a1d153e4ff3c681fb72a4290c575a52bdb6d2e9.