+dbeam@ in case it might be MD-Settings-related

+chrisha for session restore

I don't think closing the window is considering "leaving off" on ChromeOS.  I think it's interpreted as closing all the tabs individually (I guess).  Think the same thing happens on Mac when you close the window but the app's still running (still an active Chrome icon in the finder).

If you do Ctrl+Shift+q x 2 (i.e. log out) on ChromeOS, does it work as you'd expect (session restore)?

Ahh. Yes - if I log out with a browser window open the tabs are restored as expected. 

Maybe this isn't a regression and is just a funny behavior? I also notice that context clicking the chrome icon in the shelf and using "close" we treat that the same as if you had used the window controls (X) to close the last window. 

When +hwi@, is back I'd like to revisit this ChromeOS behavior. Today it feels like my on-startup setting isn't being correctly applied, so I have a preference for the Windows beahvior. On Mac, the "Quit" vs. "Close" dynamic is a bit more complicated so we'd need to think more about that. 

+1 on revisiting this.

chrisha & I just had a related discussion about closing a window by closing the last open tab, vs explicitly closing the window. From a user perspective these actions produce identical outcomes (window gets closed), so we think it's surprising when Chrome applies different behaviors to them. Which it used to, but since ~54 treats both as window close.

I think it's behaviour counter to user expectations, but working as designed. As rpop@ mentions, we've had some discussions about how best to handle this.