Examine source code of Car icon

{
  "manifest_version": 2,
  "name": "Car icon",
  "version": "1.0",
  "description": "Car icons are often associated with movement, freedom, modern life, transportation technology or travel.",
  "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": "{9a3fd4b8-913c-460f-8b7c-ebc1d081241e}"
    }
  }
}