If Google decides to change how they save drafts you're compromised. They also have complete control of the page so any key press or mouse movement you do they can catch.
Like we said, this is a starting point. It's open source. As with any type of security product that has a hope of being good, try and break it and let's fix it together :)
I believe that Google does releases of the entire application at once so this method should detect when a roll-out has occured.