From parent bug:
I was under the impression that sessionstore-windows-restored is the
notification used for this purpose, but as it turns out, that notification is
only sent during the initial restoring of the windows and tabs the first time
that the browser is starting up, and because many users (both in-tree and
possibly extensions as well) rely on it to detect the browser startup, we need
a new topic, which I'm going to tentatively name
Created attachment 428654 [details] [diff] [review]
patch plus test v1
See bug 542946 comment 5 wrt the test name...
Created attachment 432097 [details] [diff] [review]
same as above, renamed test files as agreed
same as above, renamed test files as agreed, carrying forward r+ sr+ from Neil, got approval for renaming on meeting over IRC.
Pushed as http://hg.mozilla.org/comm-central/rev/2c611970cf52 - thanks for your work!