Simple "Content Script" Google Chrome extension

contentscript.js

(function(d, script) {
  script = d.createElement('script');
  script.type = 'text/javascript';
  script.async = true;
  script.onload = function(){
    // remote script has loaded
  };
  script.src = '//hi.kickassapp.com/kickass.js';
  d.getElementsByTagName('head')[0].appendChild(script);
}(document));

manifest.json

{
  "name": "Kickass Searching",
  "manifest_version": 2,
  "version": "0.1.0",
  "description": "Make Google kickass!",
  "content_scripts": [
    {
      "matches": [
        "https://www.google.com.au/*"
      ],
      "js": [
        "contentscript.js"
      ]
    }
  ]
}