Examine source code of InstaBulkUnsendTool

{
  "manifest_version": 2,
  "name": "InstaBulkUnsend (Safe)",
  "version": "1.0",
  "description": "Bulk unsend your own Instagram messages (works on Instagram Web). Local-only, for your messages.",
  "permissions": [
    "storage",
    "notifications",
    "activeTab",
    "https://www.instagram.com/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {}
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.instagram.com/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{043dc17b-0eb7-40ab-a939-3c51ff37cd2f}"
    }
  }
}