Examine source code of cswhois

{
  "manifest_version": 2,
  "name": "cswhois",
  "description": "Lookup CS2 players in other databases",
  "version": "0.0.4",
  "browser_specific_settings": {
    "gecko": {
      "id": "extension@cswho.is",
      "strict_min_version": "58.0"
    }
  },
  "permissions": [
    "storage",
    "*://api.steampowered.com/ISteamUser/ResolveVanityURL/v0001/*"
  ],
  "icons": {
    "256": "icons/icon.png"
  },
  "options_ui": {
    "page": "options/options.html"
  },
  "web_accessible_resources": [
    "page-content/sites.html",
    "page-content/error.html",
    "icons/*.png"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://steamcommunity.com/id/*",
        "https://steamcommunity.com/profiles/*"
      ],
      "js": [
        "sites/site-manager.js",
        "content_script.js"
      ]
    }
  ]
}