WhiteOffersApp virus ruining my Chrome!

Hello, Last night I downloaded  2 things for the game "Minecraft" and when I logged on my computer this morning I opened my google and got bombarded with ads by Offersapp.

I started searching "Norton" in google for help and now the ads are showing "Norton products." My norton Antivirus isn't finding the virus and I need it off!

- If there are any free programs or things I can do to remove it please tell me! D:

[Admin Edit: Removed hyperlinks]