Chrome already encrypts your data (on Windows at least) using your Windows login credentials using the Crypto API. If the user is not logged in, the passwords are impossible to read. If the user is logged in, all it takes is an API call run by that user to decrypt them, no reauthentication necessary (and this is why you lock your PC when you walk away). I think it is a very usable solution to the "but I save passwords to avoid remembering passwords, I don't want a master password" problem, but still keeping things secure.
I think cookies are encrypted now, too.