penders - 12:31 pm on Oct 8, 2013 (gmt 0)
Yes, you can also toggle spell checking via the right mouse / context menu on text boxes. However, I am specifically asking about grammar checking - this was a new feature a few months back.
Actually, I think I've found it... you seem to have to enable the additional option "Ask Google for suggestions". Chrome now appears to grammar check as well. However, this also changes the spell checking behaviour quite significantly? Certain words that are obviously wrong are no longer being picked up?! Maybe there is just more of a delay...?