From www.bleepingcomputer.com:
The authors of SafeBrowse, a Chrome extension with more than 140,000 users, have embedded a JavaScript library in the extension’s code that mines for the Monero cryptocurrency using users’ computers and without getting their consent.
The additional code drives CPU usage through the roof, making users computers sluggish and hard to use.
You can read more here.
Yes, Pirate bay is the mastermind behind all of this. I seen a article awhile back about pirate bay offering to help create hidden websites for bitcoin. Right away I knew that was a bad idea, short while later this little news event shows up, I must say, this will destroy alot of reputation not only for Bitcoin, but for the cryptocurrency market in general, I am not impressed at all.
Yes that’s right, the illegal website people use to illegally download illegal game of thrones, put a miner on their site. 
I think what bothers me the most about it is that this to me seems o be very grey, when you cry de centralize, honest system etc etc etc.
On a bitcoin news network I read a article around the JP announcement and then turning around sinking bitcoin price. Meanwhile scooping out bitcoins for themselves. In a nutshell this is frowned upon but not illegal because of the de centralize network, not centralized.
So where do you draw the line, now you have these miners using up your gpu, so because they are being used as an extension then this is not a hack? Once again only frowned upon, all the while creating a bad reputation for crypto currencies, one in which is by far not deserving and only being orchestrated out of jealousy and greed.
Like I said, where does the line get drawn, you cannot cry court from a centralized society to moderate your decentralized network, and then put up a fight when they want control.
As @ivan shows in this video, if the site/addon informs that is mining with your resources, I believe that can’t be considered a hack.
This (informing user or not) can be the gray line between legal and illegal.
Even though I found it very funny to what @kevintootill said:
