Examine source code of AutoAverage

{
  "description": "Extention that shows students using 'studentweb' their average grade",
  "manifest_version": 2,
  "name": "AutoAverage",
  "version": "1.1",
  "icons": {
    "48": "icons/border-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.fsweb.no/*"
      ],
      "js": [
        "averager.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{57353f83-b2fd-4821-900c-4df4b9c699d4}"
    }
  }
}