GitLab

Adds new item in the Discover feed header top-level menu for 'Manage
Activity', which leads to a web page. Also slightly refactors how menu
items that lead to web pages are handled. Only shows this item and
'Manage Interests' if the user is authenticated.

Bug: 1085419
Change-Id: I66be67659ccbc04121f0eb02657a7e20cfe66e3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2341805
Commit-Queue: Adam Trudeau-Arcaro <adamta@google.com>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795986}