PBlock+ is a Google Chrome extension that claims to be a popup blocker, but instead displays advertisements in the browser. When installed, this extension will open new tabs that display advertisements trying to sell software, push fake software updates, and tech support scams. This guide contains advanced information, but has been written in such a way so that anyone can follow it. If you are unsure how this extension was installed or are concerned other extensions or unwanted programs may be installed on your computer, you can use the removal guide below.
Source: https://www.bleepingcomputer.com/virus-removal/how-to-remove-the-pblock-adware-extension