Examine source code of Auto Tab Cleaner

{
  "manifest_version": 2,
  "name": "Auto Tab Cleaner",
  "version": "1.0",
  "description": "Automatically close unused tabs after a specified time.",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{277530c0-ada8-4cd0-b57a-0b54e6a6e91a}"
    }
  }
}