Examine source code of Online Time Reminder

{
  "manifest_version": 2,
  "name": "Online Time Reminder",
  "version": "1.0",
  "description": "Reminds you when you've been online for too long.",
  "permissions": [
    "notifications",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_action": {
    "default_popup": "options.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{febbc453-4526-4395-a708-756ffe015c31}"
    }
  }
}