Examine source code of Chromecast Ultimate

{
  "manifest_version": 3,
  "name": "Chromecast Ultimate",
  "version": "5.5.0",
  "description": "Cast videos and mirror tabs to Chromecast devices directly from Firefox",
  "permissions": [
    "activeTab",
    "tabs",
    "scripting",
    "storage",
    "nativeMessaging",
    "cookies",
    "webRequest"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon.svg"
  },
  "icons": {
    "48": "icons/icon.svg",
    "96": "icons/icon.svg",
    "128": "icons/icon.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "cast-button.js"
      ],
      "css": [
        "cast-button.css"
      ],
      "run_at": "document_idle",
      "all_frames": true,
      "match_about_blank": true
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "host_permissions": [
    "<all_urls>",
    "http://192.168.0.0/16/*",
    "http://10.0.0.0/8/*",
    "http://172.16.0.0/12/*",
    "http://localhost:5000/*",
    "http://127.0.0.1:4269/*",
    "http://localhost:4269/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "chromecast-ultimate@firefox",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}