Examine source code of YouTube Night Mode

{
  "name": "YouTube Night Mode",
  "short_name": "YouTube Dark Mode",
  "manifest_version": 2,
  "version": "1.0.0.1",
  "description": "We bring to you a very beautiful YouTube Dark Mode. This is a modern design of dark mode for YouTube.",
  "browser_action": {
    "default_icon": "48.png",
    "default_title": "Turn On YouTube Dark Mode"
  },
  "background": {
    "page": "bgr.html",
    "persistent": false
  },
  "permissions": [
    "tabs",
    "activeTab",
    "storage",
    "<all_urls>"
  ],
  "icons": {
    "16": "16.png",
    "32": "32.png",
    "48": "48.png",
    "64": "64.png",
    "128": "128.png"
  }
}