Examine source code of Ferret Resource Tracker

{
  "name": "Ferret Resource Tracker",
  "short_name": "FRT",
  "manifest_version": 2,
  "author": "superferret",
  "description": "Players of Catan on colonist.io can track who has which resources",
  "version": "1.1.2",
  "icons": {
    "64": "icon64.png"
  },
  "permissions": [
    "https://colonist.io/*",
    "https://hexs.io/*",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://colonist.io/*",
        "https://hexs.io/*"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_idle",
      "js": [
        "explorer.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d07f6cbb-fc6d-4fd0-a0a4-40cef957d47b}"
    }
  }
}