Examine source code of Senf

{
  "manifest_version": 2,
  "name": "Senf",
  "version": "1.9",
  "description": "Geniessen Sie gewisse Seiten auf SPON mit extra-scharfem Senf!",
  "homepage_url": "http://spin.sponspin.org",
  "icons": {
    "64": "icons/senf64.png",
    "128": "icons/senf128.png"
  },
  "permissions": [
    "tabs",
    "notifications",
    "http://*.spiegel.de/*",
    "https://*.spiegel.de/*",
    "http://*.bento.de/*",
    "https://*.bento.de/*",
    "http://*.sponspin.org/*",
    "https://*.sponspin.org/*"
  ],
  "browser_action": {
    "default_icon": "icons/senf48empty.png",
    "default_title": "Ist doch alles Wurst!"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.spiegel.de/*",
        "*://*.bento.de/*",
        "*://*.sponspin.org/*"
      ],
      "js": [
        "jquery.js",
        "showURL.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "jquery.js",
      "background.js"
    ]
  }
}