chrome extension using a content script to access the `window` object

.manifest

{
  "content_scripts": [
    {
      "matches": ["http://*/*", "https://*/*"],
      "js": ["inject.js"],
      "all_frames": true
    }
  ],
  "web_accessible_resources": [
    "content.js"
  ]
}

content.js

console.log(window);

inject.js

/**
 * injectScript - Inject internal script to available access to the `window`
 *
 * @param  {type} file_path Local path of the internal script.
 * @param  {type} tag The tag as string, where the script will be append (default: 'body').
 * @see    {@link http://stackoverflow.com/questions/20499994/access-window-variable-from-content-script}
 */
function injectScript(file_path, tag) {
    var node = document.getElementsByTagName(tag)[0];
    var script = document.createElement('script');
    script.setAttribute('type', 'text/javascript');
    script.setAttribute('src', file_path);
    node.appendChild(script);
}
injectScript(chrome.extension.getURL('content.js'), 'body');