I would suggest you to go to the chrome browser settings and then go to 'Extensions' and disable/delete the unknown extensions which might have been downloaded accidently.
I think this should solve the problem!
It can be done by following some simple steps given below by me-
1. Type in google add ons for google chrome.
2. Now open the official site of google chrome.
3. Now in search option type- "Ads blocker" and search it.
4. Now find the suitable extension download it and then install it on your browser and restart browser if required.
Hope that this will solve your problem and you will not face this problem again in future.