Comment 5 for bug 1892724

Verified working.
For convenience I used a slightly different testing method than the test case in the bug description: I downloaded and installed (with `dpkg -i`) the chromium-browser, chromium-browser-l10n and chromium-codecs-ffmpeg-extra debs from https://launchpad.net/~canonical-chromium-builds/+archive/ubuntu/stage/+sourcepub/11549449/+listing-archive-extra (version 85.0.4183.83-0ubuntu0.18.04.1, currently awaiting sponsoring to bionic-security) in a fully up-to-date focal VM. I then ran `sudo apt update` to verify that no update was available for chromium-browser. I then enabled focal-proposed for universe and verified that the update to chromium-browser 1:85.0.4183.83-0ubuntu0.20.04.1 was available, installed it with `sudo apt install chromium-browser`, and checked that this installed the chromium snap as expected. I then verified that chromium-browser launches and works as expected.