I had trouble today with the setup described in my post from 8/27/2016.
My Raspberry Pi was unable to access localStorage since I had used the "--incognito" switch to disable popups...
To set up Chromium to auto start you have to modify the appropriate LXDE-pi/autostart file (see my 8/27 post).
In that post I noted you should add the following lines to the file (again thanks to Dan Purdy)...
@sed -i 's/"exited_cleanly": false/"exited_cleanly": true/' ~/.config/chromium/Default/Preferences
@chromium-browser --noerrdialogs --kiosk http://www.SiteToDisplay.com" --incognito
Using these two lines did prevent any popups, but also prevented access to localStorage.
The solution I discovered was to use this line in place of those two above:
@chromium-browser --disable-session-crashed-bubble --disable-infobars --kiosk http://www.SiteToDisplay.com
After rebooting my RPi it auto launched chromium in kiosk mode, did not display any error messages (about not shutting down correctly) and yes, did successfully access localStorage - problem solved.
