Fairly often (over 20 times for me so far with various kernel versions), when I reboot after a crash, my google-chrome profile is damaged in one of 2 ways:
1) open tabs don't reopen
2) google-chrome says that my profile is corrupted.

In both cases rsyncing ~/.config/google-chrome from the last hourly snapshot has fixed the problem every time.

Given that, I would say that google-chrome does not have a bug of half unclean states since the state present in a snapshot has always worked for me, but that's anecdotal, not proof.

But if my kernel hangs due to a bug that isn't btrfs' fault and I need to power off and back on, after reboot my google-chrome profile is almost always broken in some way.
This with a samsung evo 840 SSD which I believe does reasonable enough things on power shutdowns, although I can't prove that.

File formats are some kind of raw data and sqlite 3.x
~/.config/google-chrome-beta/Profile 1:
Last Session:                     data
Last Tabs:                        data
Login Data:                       SQLite 3.x database

Marc