Examine source code of GameSenseXPro fps display

{
  "manifest_version": 3,
  "name": "GameSenseXPro",
  "version": "1.1",
  "description": "FPS meter and game enhancer tools for pro gamers.",
  "permissions": [
    "scripting",
    "activeTab",
    "tabs"
  ],
  "action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "48": "assets/icons/icon-48.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "assets/icons/icon-48.png",
    "128": "assets/icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "gamesensexpro@shivansh.in"
    }
  }
}