Firefox Add-on SDK open tab on first run
===

I am using the Firefox Add-on SDK, and I am attempting to open a tab as soon as my Firefox extension gets installed for the first time. The code below is in my main.js, but it doesn't seem to work. Any tips? 

main.js:

    var ss = require("simple-storage");
    var tabs = require('tabs');
    
    if (ss.storage.firstRun == undefined) {
    	ss.storage.firstRun = false;
    	alert('First run');
    	tabs.open("http://www.google.com");	
    }