Save daily usage data into sync storage with date as key:
    Saved  _2014/06/17 {"duration":85094,"updated":"_2014/06/17 17:16:20"}

Switch between fb & non_fb url to trigger timer on or off.Even minimize the window can stop the timer now. But Couldn't restart the timer after window maximized.

Try to find a way!
Fix the issue of popup dialog not showing the correct suggestion message.
Fix the issue of can't properly start tracking while chrome window focus change.
Fix the issue of popup dialog not showing correct date.