Examine source code of MK Media Controller

{
  "manifest_version": 3,
  "name": "MK Media Controller",
  "version": "1.5",
  "description": "Modern media controller for Firefox.",
  "permissions": [
    "tabs",
    "scripting",
    "storage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "icons": {
    "48": "icons/icon-48-black.png",
    "96": "icons/icon-96-black.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "mkmediacontrol@mk2010gamer.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon-48-black.png",
    "theme_icons": [
      {
        "light": "icons/icon-48-white.png",
        "dark": "icons/icon-48-black.png",
        "size": 16
      },
      {
        "light": "icons/icon-96-white.png",
        "dark": "icons/icon-96-black.png",
        "size": 32
      }
    ]
  }
}