Examine source code of Tab Deduplicator

{
  "manifest_version": 2,
  "name": "Tab Deduplicator",
  "version": "1.3.4",
  "description": "Prevents unintentional duplicate tabs while allowing intentional ones.",
  "permissions": [
    "tabs",
    "webNavigation",
    "notifications",
    "<all_urls>",
    "sessions"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "tabdeduplicator@example.com"
    }
  }
}