Examine source code of Folder icon

{
  "manifest_version": 2,
  "name": "Folder icon",
  "version": "1.0",
  "description": "Icon of data storage such as files, images, documents... used in operating systems (Windows, macOS, Linux) to manage files.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Click me!"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f4d6aa7-144b-41aa-bfce-238e51fa9de8}"
    }
  }
}