Examine source code of Friv5Online.com

{
  "name": "Friv5Online.com",
  "description": "Quick launch for Friv5Online.com website and games.",
  "version": "1.3",
  "manifest_version": 2,
  "permissions": [
    "https://friv5online.com/"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "/images/icon16.png",
      "32": "/images/icon32.png",
      "48": "/images/icon48.png",
      "128": "/images/icon128.png"
    }
  },
  "icons": {
    "16": "/images/icon16.png",
    "32": "/images/icon32.png",
    "48": "/images/icon48.png",
    "128": "/images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "addon@friv5online.com",
      "strict_min_version": "48.0"
    }
  }
}