Examine source code of TKAN

{
  "manifest_version": 3,
  "name": "tkan",
  "version": "1.0",
  "description": "answer checker for Tae Kim's Guide to Learning Japanese",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://guidetojapanese.org/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "action": {
    "default_title": "tkan",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/16x16.png",
      "48": "images/48x48.png",
      "128": "images/128x128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "tkan@sujalwastaken"
    }
  }
}