Examine source code of StreamSpeed

{
  "manifest_version": 3,
  "name": "StreamSpeed",
  "description": "Adjust playback speed and volume",
  "version": "4.1.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{1d306bd2-9c54-481e-afbd-89ac1d45b34e}"
    }
  },
  "action": {
    "default_icon": {
      "16": "images/play16.png",
      "19": "images/play19.png",
      "38": "images/play38.png",
      "48": "images/play48.png",
      "128": "images/play128.png"
    },
    "default_popup": "popup.html",
    "default_title": "StreamSpeed"
  },
  "permissions": [
    "activeTab",
    "scripting"
  ]
}