Cherry-picking hangouts.google.com whitelisting change into M52.

Cherry-picking hangouts.google.com whitelisting change into M52.

Urgent: whitelist hangouts.google.com further (should've been done in issue 1552383002 from Dec 2015, but...) to allow video effects plugin access; tag on meet.google.com for a similar purpose; tax: refactor whitelist checks into separate thing.

R=sky@chromium.org,tsepez@chromium.org
BUG=614062
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/1974413003
Cr-Commit-Position: refs/heads/master@{#395172}
(cherry picked from commit 81dcbd6123178d58c5edc53d1453e03f9afa31ca)

[qaz-chromium, 2016-05-24 20:37:14]

qaz@chromium.org changed reviewers:
+ qaz@chromium.org

[qaz-chromium, 2016-05-24 20:37:14]

Manually cherry-picking... Thanks.

[sky, 2016-05-24 20:57:01]

Why aren't you using drover?

[qaz-chromium, 2016-05-24 21:16:22]

On 2016/05/24 20:57:01, sky wrote:
> Why aren't you using drover?

I did, but got a permission denied error since I'm not a committer.

[sky, 2016-05-24 21:36:23]

Got it, LGTM

[qaz-chromium, 2016-05-24 21:49:17]

The CQ bit was checked by qaz@chromium.org

[commit-bot: I haz the power, 2016-05-24 21:49:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2011623002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/2011623002/1

[commit-bot: I haz the power, 2016-05-24 21:51:25]

Committed patchset #1 (id:1)