Examine source code of hsgr-status-checker

{
  "description": "Adds a browser icon that shows if hackerspace.gr is open, it displays a counter of people inside.",
  "manifest_version": 2,
  "name": "hsgr-status-checker",
  "version": "0.1.7resigned1",
  "homepage_url": "https://hackerspace.gr",
  "icons": {
    "32": "icons/hsgr-32.png"
  },
  "applications": {
    "gecko": {
      "id": "elkos@hackerspace.gr",
      "strict_min_version": "45.0"
    }
  },
  "background": {
    "scripts": [
      "jquery.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/hsgr-32.png",
    "default_title": "hsgr status",
    "default_popup": "popups/popup.html"
  }
}