[snap] update hides the running browser

[Simon Déziel]

Problem description:

I had a couple of tabs open in incognito mode and the Chromium window was minimized/didn't had the focus. Suddenly, the desktop icon vanished then reappeared, but the new icon indicated that Chromium was not running (no "dot"/running indicator next to the icon) so I couldn't get to my old tabs/session.

Steps to reproduce:

1) install chromium from snap
snap install chromium
2) open chromium in incognito mode
3) open a site in a tab
4) minimize the browser
5) wait for snap to refresh the chromium version
6) notice that you can't access the browser executing from
   the old snap version as it's no longer visible from the
   launcher, only the new one is there

Workaround:

1) start chromium from the new snap
2) open the "task manager"
3) double-click on one of the process tied to an old tab from the previous snap version

Additional information:

# snap info chromium
name: chromium
summary: Chromium web browser, open-source version of Chrome
publisher: Canonical✓
contact: https://bugs.launchpad.net/ubuntu/+source/chromium-browser/+bugs?field.tag=snap
license: unset
description: |
  An open-source browser project that aims to build a safer, faster, and more stable way for all
  Internet users to experience the web.
commands:
  - chromium
snap-id: XKEcBqPM06H1Z7zGOdG5fbICuf8NWK5R
tracking: edge
refresh-date: today at 08:39 EST
channels:
  stable: 72.0.3626.96 2019-02-13 (595) 153MB -
  candidate: 72.0.3626.109 2019-02-15 (606) 153MB -
  beta: 73.0.3683.46 2019-02-21 (618) 153MB -
  edge: 74.0.3710.0 2019-02-21 (617) 154MB -
installed: 74.0.3710.0 (617) 154MB -

# dpkg -l snapd | grep snap
ii snapd 2.37.1.1+18.04 amd64 Daemon and tooling that enable snap packages

# lsb_release -rd
Description: Ubuntu 18.04.2 LTS
Release: 18.04