Examine source code of Konkur Countdown

{
  "manifest_version": 2,
  "name": "Konkur Countdown",
  "version": "1.3.0",
  "description": "تا ماراتن کنکور چند روز باقی مانده است؟",
  "icons": {
    "48": "images/logo48.png",
    "96": "images/logo96.png"
  },
  "browser_action": {
    "default_icon": "images/logo.png",
    "default_title": "Konkur Countdown",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.mozilla.org/*"
      ],
      "js": [
        "popup.js"
      ],
      "css": [
        "popup.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{e3878d83-e64d-4e29-83b4-02f265a2dc3b}"
    }
  }
}