Add test runner support for overriding web_security_enabled preference.

Add test runner support for overriding web_security_enabled preference.

Have TestRunner::OverridePreference() recognize "WebKitWebSecurityEnabled"
as a boolean preference which controls the web_security_enabled web
preference.

R=mkwst,jochen
BUG=254993
Committed: https://crrev.com/b45d62cc833513e74b1550284900e3c52f93706a
Cr-Commit-Position: refs/heads/master@{#296543}

[sof, 2014-09-23 21:47:33]

sigbjornf@opera.com changed reviewers:
+ jochen@chromium.org, mkwst@chromium.org

[sof, 2014-09-23 21:47:33]

Please take a look.

I couldn't find a way to control the webSecurityEnabled setting from layout
tests, hence this.

(Needed for https://codereview.chromium.org/594803002/ testing.)

[Mike West, 2014-09-24 08:43:45]

LGTM. Though I question the value of having the pref in the first place, we do
have it, so we should make sure it works correctly (you'll still need a
Jochen-like reviewer to stamp this).

[sof, 2014-09-24 11:12:52]

On 2014/09/24 08:43:45, Mike West wrote:
> LGTM. Though I question the value of having the pref in the first place, we do
> have it, so we should make sure it works correctly (you'll still need a
> Jochen-like reviewer to stamp this).

Thanks, yes - it seems worth having some test coverage (and couldn't find any.)

[jochen (gone - plz use gerrit), 2014-09-24 20:05:14]

lgtm

[sof, 2014-09-24 21:32:07]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2014-09-24 21:32:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/601513002/1

[commit-bot: I haz the power, 2014-09-24 22:24:23]

Committed patchset #1 (id:1) as 707acbbe9d6bdeee23ae2c94a72cae98c28602ae

[commit-bot: I haz the power, 2014-09-24 22:25:11]

Patchset 1 (id:??) landed as
https://crrev.com/b45d62cc833513e74b1550284900e3c52f93706a
Cr-Commit-Position: refs/heads/master@{#296543}