Examine source code of Miyabi Wallpaper

{
  "manifest_version": 2,
  "name": "Miyabi Wallpaper for Firefox",
  "version": "1.0",
  "description": "Automatically change wallpaper every time you open a new tab.",
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "permissions": [],
  "web_accessible_resources": [
    "background/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{70d6e8e2-1f8d-4d4b-9cad-8c6c6c187b88}"
    }
  }
}