Examine source code of The Clock

{
  "name": "The Clock",
  "version": "1.1",
  "description": "The clock Firefox's Add-On shows time and date quickly. It has background images correspond to the periods of a day.",
  "permissions": [],
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/logo/date-time-16.png",
      "32": "images/logo/date-time-32.png",
      "48": "images/logo/date-time-48.png",
      "128": "images/logo/date-time-128.png"
    },
    "default_title": "Getting Started Example"
  },
  "icons": {
    "16": "images/logo/date-time-16.png",
    "32": "images/logo/date-time-32.png",
    "48": "images/logo/date-time-48.png",
    "128": "images/logo/date-time-128.png"
  }
}