Examine source code of Tickify

{
  "manifest_version": 2,
  "name": "Tickify",
  "version": "1.1",
  "description": "Cambia el color del tick de verificación de WhatsApp.",
  "icons": {
    "48": "icons/tick.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/tick.png",
    "default_title": "Tickify",
    "default_popup": "popup/ChooseColor.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://web.whatsapp.com/*"
      ],
      "js": [
        "tickify.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{99e7af0e-2923-40a8-8a97-23cdd49ed7ae}"
    }
  }
}