I spent the whole morning trying to make the chrome database api work, which is called "gears". However I failed. And it turned out that google no longer update the api and has removed gears since chrome 12. (I am currently using chrome 17, source: http://gearsblog.blogspot.com.au/2011/03/stopping-gears.html).
The reason why google give gears up is that it is a fast move by google to implement the web database and other web technologies. However, since now html5 is globally available, which is a standard to provide all the technologies provided by gears, google shift its focus to html5.
I'll get started with html5 tonight.