I am running Ubuntu Gnome 15.04, with Gnome Shell, and 3.16, although I only just upgraded to Gnome 3.16 from Gnome 3.14. And sometime during the upgrade I suddenly noticed this in Firefox:
It just suddenly appeared before the upgrade was finished (it was in the unpacking stage), and after looking here it appears to be something to do with syncing, but I don't use syncing, so what is this? And why did I suddenly get it? Also, after a restart, it has disappeared, and my syncing settings seam off as usual.
Information Update:
It couldn't be related to this in any way now could it: CVE-2015-4495?
OS Information:
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 15.04
Release: 15.04
Codename: vivid
Package Information:
firefox:
Installed: 39.0+build5-0ubuntu0.15.04.1
Candidate: 39.0+build5-0ubuntu0.15.04.1
Version table:
*** 39.0+build5-0ubuntu0.15.04.1 0
500 http://gb.archive.ubuntu.com/ubuntu/ vivid-updates/main amd64 Packages
500 http://security.ubuntu.com/ubuntu/ vivid-security/main amd64 Packages
100 /var/lib/dpkg/status
37.0+build2-0ubuntu1 0
500 http://gb.archive.ubuntu.com/ubuntu/ vivid/main amd64 Packages