Examine source code of ReYoutube

{
  "manifest_version": 2,
  "name": "ReYoutube",
  "version": "1",
  "description": "Adds comments for youtube video that disabled commenting",
  "icons": {
    "512": "icons/favicon.png"
  },
  "permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "browser_action": {
    "default_icon": "icons/favicon.png",
    "default_title": "ReYoutube",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*",
        "*://www.youtube.de/*"
      ],
      "js": [
        "extension.js"
      ],
      "css": [
        "reYoutube.css"
      ]
    }
  ]
}