Examine source code of Toggle Fullscreen

{
  "manifest_version": 3,
  "name": "Toggle Fullscreen",
  "version": "0.1.1",
  "description": "Toggle fullscreen mode for the current window.",
  "browser_specific_settings": {
    "gecko": {
      "id": "@toggle-fullscreen",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "scripting",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "Toggle Fullscreen"
  }
}