Examine source code of Virgoolak

{
  "description": "Virgool screenshoot builder",
  "manifest_version": 2,
  "name": "Virgoolak",
  "version": "1.1",
  "homepage_url": "https://virgoolak.ir",
  "icons": {
    "48": "icons/virgoolak-16.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/virgoolak-16.png",
      "32": "icons/virgoolak-16.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.virgool.io/*/*"
      ],
      "js": [
        "virgoolak.js"
      ]
    }
  ]
}