Implement policy_PopupsAllowedForUrls test in AutoTest.

Test verifies the behavior of Chrome OS for a range of valid values
in the PopupsAllowedForUrls user policy, with DefaultPopupsSetting=2
(i.e., block pop-ups on all pages, except for those with URLs listed
in PopupsAllowedForUrls). The range of valid values is covered using
four unique test cases: NotSet_Blocked, 1Url_Allowed, 2Urls_Blocked,
and 3Urls_Allowed.

BUG=chromium:572947
TEST=Run test_that <IP> policy_PopupsAllowedForUrls

Change-Id: Ia34f702f01621ad3e6f600fd7b6655e9d553e5a9
Reviewed-on: https://chromium-review.googlesource.com/319635
Commit-Ready: Scott Cunningham <scunningham@chromium.org>
Tested-by: Scott Cunningham <scunningham@chromium.org>
Reviewed-by: Scott Cunningham <scunningham@chromium.org>
4 files changed