Examine source code of Keep Page Active

{
  "manifest_version": 2,
  "name": "Keep Page Active",
  "version": "0.5",
  "description": "Keeps chosen page active.",
  "icons": {
    "48": "icons/infinity-48.png"
  },
  "permissions": [
    "alarms",
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/infinity-48.png",
    "default_title": "Keep Page Active",
    "default_popup": "options.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}