Examine source code of Site Marker

{
  "manifest_version" : 3 ,
  "name" : "Site Marker",
  "version" : "1.0",
  "description" : "Mark websites with your own notes (e.g. fraud warnings) and get reminded whenever you revisit them.",
  "developer": {
    "name" : "Bitangsha Ray",
    "url": "https://plaintextlab.org"
  },
  "permissions" : [
    "storage" ,
    "tabs" ,
    "scripting" ,
    "unlimitedStorage" 
  ],
  "host_permissions" : [
    "<all_urls>" 
  ],
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "action" : {
    "default_popup" : "popup.html",
    "default_title" : "Site Marker"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "site-marker@local.extension",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}