Examine source code of Full Screen withoupi

{
  "manifest_version": 2,
  "name": "Full Screen without Title/URL Bar",
  "version": "1.1",
  "description": "Full Screen content without Title Bar / URL Bar / Tabs",
  "homepage_url": "https://rahulvarale.github.io/",
  "icons": {
    "16": "icons/icon_16x16.png",
    "32": "icons/icon_32x32.png",
    "64": "icons/icon_64x64.png",
    "128": "icons/icon_128x128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon_16x16.png",
      "32": "icons/icon_32x32.png",
      "64": "icons/icon_64x64.png",
      "128": "icons/icon_128x128.png"
    }
  },
  "permissions": [
    "tabs",
    "http://*/*",
    "https://*/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8effe035-84f8-40f4-a643-09a3e4e992b2}"
    }
  }
}