Here I use VIPRE Internet Security now updated to the 2016 build and never run into that type of crub on FB at least while out on the web VIPRE's firewall and the web filtering seen with that block suspect sites. I don't think Malwarebytes and Kaspersky are quite doing the job for you while this stuff is geared to get past most system protections you can think of by just how the coding is worked out to be cleverly hidden.
Addons are typically opening doors up for exploits which is likely what you have there! Lately Chrome has been getting some negative reviews in that area as well. Running with the 44.02 FF presently while I ran with the Waterfox and Cyberfox variants without running into that type of problem. The laptop that got hit a few years back with VIPRE on that as well saw Chrome installed by one of the kids as the parent complained about. The father won't loan his out and the laptop got snared with scamware! All the kid had to do was click on the wrong thing and whamo! "Saw ya comin'! he he he he he he..." all the way to the bank!
Update: I only have 3 extensions namely Adblock, Google Docs, and Ublock Origin. I deleted the three, and tried logging in and still no dice. So those three extensions are back on Chrome.
If all else fails, I will try Vipre. The thing is, I just renewed my KIS so my money would go down the drain.
I suspect you already have the bug tucked away somewhere on your system there possibly an unknown file stashed in sub folder under your user account! I've been finding that is a typical "you would never look for it there" type of hiding place for catching the one file that serves multiple purposes including trojan downloading.
The free trial for the 30day free trial for VIPRE Internet Security 2016 as well as for the regular av program without firewall and web filtering requires a working email address where they send out the temp key you enter once the download is installed. If you decide to give it a try you will be prompted to either remove or allow VIPRE to remove any other av programs which is common place anyways where one program goes to allow another one on.
I had friend who didn't even believe it was worth looking at when I was first pointed to this particular software until they tried it out and now won't part from it! One friend went for the life time license offer having found it finds things in folders as well as filters sites. That is the type of deep scanning ability you are probably going to need if there was bug planted on you which it sounds like.
update: I did another full scan of KIS and still found nothing. I was contemplating on uninstalling KIS and replacing it with Vipre but I opted to uninstall (using Revo) Chrome to take it out of the equation. Used Firefox for one whole day and just reinstalled Chrome. Logged in and the problem was gone. I'm guessing Chrome was hijacked at some point and completely uninstalling it removed the malware as well. I've taken a liking to Firefox again (I used it before Chrome) and I will be using it for now. Although I miss the sync feature of Chrome.
VIPRE is still great one to go with if you are looking for a paid program some time! The removal and reinstall of Chrome seeing the bug gone points to something mocking an addon and something you could run into again if you were not able to identify just what put it there in the first place! I suggest you use caution in that area so you won't end up being bugged all over again?! At least you have a positive report!