Context menus in Chrome extensions

Script should look like this:

function getword(info,tab) {
  console.log("Word " + info.selectionText + " was clicked.");
  chrome.tabs.create({  
    url: "http://www.google.com/search?q=" + info.selectionText
  });
}
chrome.contextMenus.create({
  title: "Search: %s", 
  contexts:["selection"], 
  onclick: getword
});

And manifest.json:

{
    "name": "App name",
    "version": "1.0",
    "manifest_version": 2,
    "description": "Your description",
    "permissions": [
      "contextMenus"
     ],
    "background": { 
      "scripts": ["script.js"]
    }
}

Here you have how to load extension: http://developer.chrome.com/extensions/getstarted.html