I started to have this problem which has been notified elsewhere on this forum. Avast stops working, message “Background services not running”, clicking “repair” or switching back on results in a restart of pc being recommended. I run Windows 10, fully updated, and Chrome also fully updated. I did notice a pattern that this occurred when I accessed my Yahoo Mail. I accessed it through the browser (Chrome) and sometimes folders would not open which was when I checked the Avast tray icon to see the red x showing that it had switched off. I then decided to download the Yahoo Mail app for Windows 10 and only access my emails though that method. So far I have not had any problem and Avast has not switched itself off. I will report back if I have any future problems.
I don’t see Avast turning itself off for any valid reason, Chrome browser or not. ???
It is good your issue apparently is resolved however if it were me I would uninstall the added app you downloaded, do a “Repair” of your Avast installation and see if the problem is resolved without the added app.
If not you can always re install that app.
REPAIR and RESET Avast Installation
https://www.avast.com/faq.php?article=AVKB204