I use the new built-in "Users" feature of Chrome to switch between Home/Work accounts easily. However, Chrome remembers the "last" user profile you had selected when launching new windows. This is a problem if I close down my "Home" profile last, because when I then click the Email shortcut on my taskbar, because it goes to mail.mycompany.com using my Home profile, and I'm not logged in.
I'd like to change the shortcut to the company webmail to pass a switch that tells Chrome to always start as the "Default" user, regardless of the last one used.
Note: I have tried user-data-dir, and this seems to do something very different, completely isolated from the Users functionality built in to Chrome. It's possible I'm using it wrong, but please test this before assuming it does the same thing and posting an answer ;-)