“Previous networks” item gives no indication that there aren’t any

Ubuntu 15.04 r270

1. In System Settings, navigate to “Wi-Fi” > “Previous networks”.
2. Remove any networks from the list, by selecting each and choosing “Forget This Network”.
3. Return to the “Wi-Fi” screen.

What you see: A “Previous networks” item that gives no indication that there aren’t any.

This needs design work. Possible solutions, when there aren’t any remembered previous networks:
a. Don’t show the “Previous networks” item at all. (Drawback: Might be confusing if you deleted them all, exited, and couldn’t re-enter.)
b. Show it, but disabled. (Drawback: As above.)
c. Show it with a summary value. (Drawback: Most of the time the value will not be interesting. Who cares whether there are 24 or 27 previous networks?)

[Originally reported by Michi Henning. <https://lists.launchpad.net/ubuntu-phone/msg18978.html>]