Examine source code of Work Time Tracker

{
  "manifest_version": 2,
  "name": "Work Time Tracker",
  "version": "1.0",
  "description": "Track actual work time spent while the browser is active.",
  "permissions": [
    "storage",
    "idle"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Work Time Tracker",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d038766e-331c-4c05-9869-70b726d81caa}"
    }
  }
}