I don't use Chrome -- can't stand the interface (saying I don't like it is an understatement).
Hopefully someone else can help you.
In the meantime, I found this YouTube video about thumbnails in Chrome
http://www.youtube.com/watch?v=6TL5h_TqJIUDoes it work for the current version of Chrome? I have no idea because I don't use Chrome, but it's something to try.