[Merge M-53] Error out when merchant requests only unknown payment methods.

[Merge M-53] Error out when merchant requests only unknown payment methods.

If the merchant requests only payment methods that Chrome does not
support, then reject the show() promise with NotSupportedError.

BUG=628460
Review-Url: https://codereview.chromium.org/2149023005
Cr-Commit-Position: refs/heads/master@{#406460}
(cherry picked from commit 3748272dc88b06912bf432655587dc7dd4a4a561)

Committed: https://chromium.googlesource.com/chromium/src/+/500a18cd9552ec468efb13d706a8350ba6ad5e29

[please use gerrit instead, 2016-07-21 17:57:21]

Description was changed from

==========
[Merge M-53] Error out when merchant requests only unknown payment methods.

If the merchant requests only payment methods that Chrome does not
support, then reject the show() promise with NotSupportedError.

BUG=628460

Review-Url: https://codereview.chromium.org/2149023005
Cr-Commit-Position: refs/heads/master@{#406460}
(cherry picked from commit 3748272dc88b06912bf432655587dc7dd4a4a561)
==========

to

==========
[Merge M-53] Error out when merchant requests only unknown payment methods.

If the merchant requests only payment methods that Chrome does not
support, then reject the show() promise with NotSupportedError.

BUG=628460

Review-Url: https://codereview.chromium.org/2149023005
Cr-Commit-Position: refs/heads/master@{#406460}
(cherry picked from commit 3748272dc88b06912bf432655587dc7dd4a4a561)

Committed:
https://chromium.googlesource.com/chromium/src/+/500a18cd9552ec468efb13d706a8...
==========

[please use gerrit instead, 2016-07-21 17:57:23]

Committed patchset #1 (id:1) manually as
500a18cd9552ec468efb13d706a8350ba6ad5e29.