Examine source code of Hide Messenger Banner

{
  "manifest_version": 3,
  "name": "Hide Messenger Banner",
  "version": "1.0",
  "description": "Hides distracting banner elements in FB Messenger",
  "browser_specific_settings": {
    "gecko": {
      "id": "@fc80a9e4-627b-11f1-84e2-c76edd8dc0c2",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/messages/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}