This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
Both Firefox and Chrome offer users privacy features which will cause Web Storage to be non-persistent across browser restart. For example Firefox has a "Never remember history" option, and Chrome has a "clear cookies and other data when I close my browser" option. For an application developer, it would be helpful to know when such features have been enabled, so that the application can inform the user, assist in troubleshooting, or disable features that depend on persistent storage.
Given that such features are generally implemented for users with, shall we say, a more emphatic belief in privacy, it seems likely that they would also not want sites to be able to tell if storage was disabled. It seems reasonable for the UA to remind the user though ("this site is storing data, be aware that it will be blown away when you close the browser" or some such). But that's out of scope for the spec.