Examine source code of Error icon

{
  "manifest_version": 2,
  "name": "Error icon",
  "version": "1.0",
  "description": "Error icons are commonly used to display system problems, warnings, or error messages.",
  "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": "{d641e8d2-4cc0-49a6-a7da-ab9d24fb58a3}"
    }
  }
}