user activity: Unit tests for group extra CWP functions.

BUG=None
TEST=None

Change-Id: I6454b4f55a3c47387b1b2cc35342358937026cfb
Reviewed-on: https://chrome-internal-review.googlesource.com/282200


Commit-Queue: Evelina Dumitrescu <evelinad@google.com>
Tested-by: Evelina Dumitrescu <evelinad@google.com>
Reviewed-by: George Burgess <gbiv@google.com>
Reviewed-by: Ting-Yuan Huang <laszio@google.com>
Reviewed-on: https://chromium-review.googlesource.com/435906


Commit-Ready: Luis Lozano <llozano@chromium.org>
Tested-by: Luis Lozano <llozano@chromium.org>
Reviewed-by: Luis Lozano <llozano@chromium.org>