Examine source code of Link Labeler

{
  "manifest_version": 2,
  "name": "Link Labeler",
  "version": "1.0",
  "description": "Adds icons before links based on their type (PDF, HTTPS, magnet, etc).",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{94150817-bf24-4b01-a5a8-be04fc8d63fb}",
      "strict_min_version": "134.0"
    }
  },
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  }
}