Examine source code of tabexpire

{
  "description": "Automatically closes any tab not accessed for 48h hours.  When a tab is closed, a bookmark is placed in tabexpire folder.",
  "manifest_version": 2,
  "name": "tabexpire",
  "version": "1.1resigned1",
  "homepage_url": "https://github.com/cfcfs/tabexpire",
  "icons": {
    "24": "icons/ic_schedule_black_24px.svg"
  },
  "permissions": [
    "tabs",
    "bookmarks",
    "storage",
    "alarms"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d68259f0-bc0f-4e72-9eda-4b6577d52a31}"
    }
  }
}