Examine source code of YouTube Time Limiter

{
  "manifest_version": 2,
  "name": "YouTube Time Limiter",
  "version": "1.0",
  "description": "Closes all YouTube tabs when any tab reaches 20 minutes",
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f999eef-0172-489b-bdba-e57af8daedd7}"
    }
  }
}