[Merge M-56] Mark IFrame support in PaymentRequest experimental

[Merge M-56] Mark IFrame support in PaymentRequest experimental

IFrame support in PaymentRequest may be better served through
FeaturePolicy. This patch marks the current IFrame support
experimental, so it's disabled by default, but developers still can
experiment with it. Once the FeaturePolicy question is resolved, the
current implementation of the IFrame support will be either shipped or
replaced by FeaturePolicy.

BUG=652148
Review-Url: https://codereview.chromium.org/2525813003
Cr-Commit-Position: refs/heads/master@{#434257}
(cherry picked from commit d2c4379ec3783f7f70b14f6fda92f13cd496bf66)

Committed: https://chromium.googlesource.com/chromium/src/+/b0db3df9ef642ede2732fe6b4f357a3b7960deff

[please use gerrit instead, 2016-11-28 15:07:28]

Description was changed from

==========
[Merge M-56] Mark IFrame support in PaymentRequest experimental

IFrame support in PaymentRequest may be better served through
FeaturePolicy. This patch marks the current IFrame support
experimental, so it's disabled by default, but developers still can
experiment with it. Once the FeaturePolicy question is resolved, the
current implementation of the IFrame support will be either shipped or
replaced by FeaturePolicy.

BUG=652148

Review-Url: https://codereview.chromium.org/2525813003
Cr-Commit-Position: refs/heads/master@{#434257}
(cherry picked from commit d2c4379ec3783f7f70b14f6fda92f13cd496bf66)
==========

to

==========
[Merge M-56] Mark IFrame support in PaymentRequest experimental

IFrame support in PaymentRequest may be better served through
FeaturePolicy. This patch marks the current IFrame support
experimental, so it's disabled by default, but developers still can
experiment with it. Once the FeaturePolicy question is resolved, the
current implementation of the IFrame support will be either shipped or
replaced by FeaturePolicy.

BUG=652148

Review-Url: https://codereview.chromium.org/2525813003
Cr-Commit-Position: refs/heads/master@{#434257}
(cherry picked from commit d2c4379ec3783f7f70b14f6fda92f13cd496bf66)

Committed:
https://chromium.googlesource.com/chromium/src/+/b0db3df9ef642ede2732fe6b4f35...
==========

[please use gerrit instead, 2016-11-28 15:07:30]

Committed patchset #1 (id:1) manually as
b0db3df9ef642ede2732fe6b4f357a3b7960deff.