Examine source code of Audible - Play in Tab

{
  "manifest_version": 3,
  "name": "Audible - Play in Tab",
  "version": "1.0",
  "description": "Adds a native-looking 'Play in Tab' button next to the standard player options in your Audible library.",
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "audible-play-in-tab@ApexAlaska.addons.mozilla.org",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.audible.com/library/titles*",
        "*://*.audible.com/pd/*",
        "*://*.audible.co.uk/library/titles*",
        "*://*.audible.co.uk/pd/*",
        "*://*.audible.ca/library/titles*",
        "*://*.audible.ca/pd/*",
        "*://*.audible.com.au/library/titles*",
        "*://*.audible.com.au/pd/*"
      ],
      "js": [
        "jquery.min.js",
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}