Currently I am able to log in and out of gmail on a friend's laptop without any (reasonable) fear that my email will keep living on that machine (and is unencrypted). Obviously keyloggers etc could grab my password, but let's assume I'm not _that_ paranoid.
I do not have this option with the Chrome browser itself. At best, I can log into Chrome (and am encouraged to do so at first startup) and at the end of the session, I can delete the profile (rm -rf
Compare this to Chrome OS. Here the functionality is built in; you don't have to delete your user account at the end of every session. Encrypted files are stored on the local drive which you can then access the next time you log in. It's quick and painless. This needs to be built into the standard Chrome browser.