Examine source code of Footy Mate

{
  "name": "Footy Mate",
  "short_name": "FootyMate",
  "description": "Football league tables, fixtures and results",
  "homepage_url": "https://www.footymate.co.uk",
  "version": "1.8.5",
  "manifest_version": 2,
  "permissions": [
    "storage"
  ],
  "icons": {
    "16": "/assets/icon-16.png",
    "48": "/assets/icon-48.png",
    "128": "/assets/icon-128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "/assets/icon-16.png",
      "48": "/assets/icon-48.png",
      "128": "/assets/icon-128.png"
    },
    "default_title": "Footy Mate",
    "default_popup": "index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{794df7f9-f373-4898-a8b7-0067634cbd49}"
    }
  }
}