Examine source code of Wikipedia

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Wikipedia",
  "version": "0.2",
  "manifest_version": 2,
  "minimum_chrome_version": "37.0.0.0",
  "permissions": [
    "webview",
    "power",
    "storage",
    "videoCapture",
    "geolocation",
    "pointerLock",
    "system.display",
    {
      "fileSystem": [
        "write",
        "retainEntries",
        "directory"
      ]
    },
    "accessibilityFeatures.read",
    "accessibilityFeatures.modify"
  ],
  "app": {
    "background": {
      "scripts": [
        "js/foam.js",
        "js/cab.js",
        "config.js",
        "background_main.js"
      ]
    }
  },
  "default_locale": "en",
  "icons": {
    "128": "img/128.png"
  }
}