Examine source code of Pacman Offline

{
  "manifest_version": 2,
  "version": "0.1.1",
  "name": "Pacman Offline Game",
  "description": "Play the classic PAC-Man (AKA Pacman) game anywhere, anytime!",
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png",
    "256": "data/icons/256.png"
  },
  "homepage_url": "https://add0n.com/pacman.html",
  "offline": true,
  "permissions": [
    "storage"
  ],
  "browser_action": {},
  "background": {
    "persistent": false,
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6480f3e1-f3d3-4576-8f51-dbd5231783c0}"
    }
  }
}