It schedules the ping to be sent on new profiles after 30 minutes
from the Firefox startup. The ping is eventually sent at shutdown
if the scheduled time wasn't reached.
To reliably prevent sending the ping more than once, the "session-state.json"
file is used to keep track of the "sent" state.
The "new-profile" ping is protected behind a pref, disabled by default
in this patch.
MozReview-Commit-ID: 4g4lPRXe9q6
6bc6b11ec3