Stop sending the 'CSP' header.

Stop sending the 'CSP' header.

The 'CSP' header is causing CORS preflights when requesting cross-origin
resources, which is going to break a certain number of CDN-hosted
resources on sites that are using CSP. That's no good at all.

Dropping the header for the moment while we work out a reasonable
solution. Ideally, we'd just be reverting the whole implementation
(https://codereview.chromium.org/1009583003/), but since we're almost
certainly going to need to merge this back, this patch leaves most of
the machinery in place, but just neuters the "shouldSendCSPHeader"
check.

See https://github.com/whatwg/fetch/issues/52 for discussion.

BUG=452819
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=195418

[Mike West, 2015-05-15 11:40:46]

The CQ bit was checked by mkwst@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-05-15 11:41:01]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1142623002/1

[Mike West, 2015-05-15 11:58:40]

mkwst@chromium.org changed reviewers:
+ mounouri@chromium.org, mvanouwerkerk@chromium.org, peter@chromium.org

[Mike West, 2015-05-15 11:58:41]

Peter, Mounir, Michael, do any of you happen to be around today? Paris and
Munich are on vacation, but it would be ideal if I could get this in before the
branch so I can avoid a merge... :)

-mike

[Michael van Ouwerkerk, 2015-05-15 12:50:06]

lgtm with nit

https://codereview.chromium.org/1142623002/diff/1/LayoutTests/http/tests/secu...
File
LayoutTests/http/tests/security/contentSecurityPolicy/resources/csp-header-is-sent.js
(right):

https://codereview.chromium.org/1142623002/diff/1/LayoutTests/http/tests/secu...
LayoutTests/http/tests/security/contentSecurityPolicy/resources/csp-header-is-sent.js:17:
}, 'CSP header is sent on resource requests for which there is a policy.');
Better update this message as well then.

[commit-bot: I haz the power, 2015-05-15 13:11:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-15 13:11:13]

Dry run: This issue passed the CQ dry run.

[Mike West, 2015-05-15 14:35:37]

The CQ bit was checked by mkwst@chromium.org

[Mike West, 2015-05-15 14:35:38]

The patchset sent to the CQ was uploaded after l-g-t-m from
mvanouwerkerk@chromium.org
Link to the patchset: https://codereview.chromium.org/1142623002/#ps20001
(title: "Nit.")

[commit-bot: I haz the power, 2015-05-15 14:35:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1142623002/20001

[commit-bot: I haz the power, 2015-05-15 19:03:51]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=195418