Examine source code of Social Site Timer

{
  "manifest_version": 3,
  "name": "Visible Site Timer",
  "version": "1.0",
  "description": "Shows a visible-time counter on selected social media sites.",
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "*://*.facebook.com/*",
    "*://*.youtube.com/*",
    "*://*.tiktok.com/*",
    "*://*.instagram.com/*",
    "*://x.com/*",
    "*://*.x.com/*",
    "*://reddit.com/*",
    "*://*.reddit.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/*",
        "*://*.youtube.com/*",
        "*://*.tiktok.com/*",
        "*://*.instagram.com/*",
        "*://x.com/*",
        "*://*.x.com/*",
        "*://reddit.com/*",
        "*://*.reddit.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "visible-site-timer@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}