Examine source code of MTXCast

{
  "name": "MTXCast",
  "description": "Opensource chromecast alternative(client app for firefox)",
  "version": "1.3",
  "manifest_version": 3,
  "icons": {
    "128": "icon.png"
  },
  "action": {
    "default_title": "MTXCast"
  },
  "content_scripts": [
    {
      "js": [
        "content.js"
      ],
      "css": [
        "casting.css"
      ],
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "contextMenus",
    "tabs"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "MTXCast@FoxRefire",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_security_policy": {
    "extension_pages": "script-src 'self';"
  }
}