AFP Virus / Malware - Your browser has been locked

Considering there are no viruses for OS X that would be impossible. If this is a popup then then you may be navigating to **** sites or downloading from torrents both of which is foolish and will eventually result in some malware being installed on your computer.

However to manage popups open Safari - Preferences - Extensions - Add Extensions and look for Ad Block, then install it.

Also properly educating yourself on OS X malware may be a smart move. I'd recommend with a couple of articles first:

Thomas Reed's Mac Malware Guide

and

Viruses, Trojans and Malware - Prevention and removal: Apple Support Communities

Force quit Safari, then open it again holding down the Shift key.

You may be able to avoid force-quitting by opening Safari Preferences - Security & un-checking 'Enable Javascript' then clicking the back button in Safari, then re-checking the box.

Unless you download & install something, or potentially, if you have java enabled... then browsing the web will not 'result in some malware being installed', no matter where you go.

This is definitely not malware. It's just a page that loads and uses some JavaScript tricks to keep you from closing it, and tries to trick you into thinking you need to pay some government authority money. See:

FBI ransomware “virus” rampant

Note that, although the scam described in that link refers to the FBI, it's still the same scam... there are numerous variants, all tailored to the authorities in your part of the world.

Actually, this particular scam has nothing to do with fake Adobe Flash update. That's an entirely separate issue, at could potentially involve malware. Did you install anything that purported to be a Flash Player update? If so, where did you find it? Still got a link in your browser history?

I got a screen saying my screen was blocked by the Australian federal police. It said I needed to pay a fine. I tried to exit the window but didn't work. I clicked enter and the screen was gone. I'm worried if my laptop has malware/virus. I don't know what to do atm. I was using chrome and an incognito window.

Thank you for the extra tip about holding down the shift key. I had this problem and used force quit, but the ransom page re-appeared when i re-opened safari. I tried using the menu options to reset safari, but the malware program kept preventing me from selecting the reset option. Using your suggestion, I force quit, then held down the shift key when re-opening safari, and voila, the ransom page was gone. I was then able to reset safari, just to be on the safe side.

Also just go to the Safari tab and selet "Reset Safari"

I'm worried if my laptop has malware/virus.

Please read all the responses here. That question has already been answered.