Examine source code of ERR_INTERNET_DISCONNECTED

{
  "name": "ERR_INTERNET_DISCONNECTED",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "ezgif-64ebc4535d27fb.gif"
    },
    "colors": {
      "frame": "rgba(27, 28, 31, 1)",
      "tab_background_text": "rgba(160, 160, 160, 1)",
      "toolbar": "rgba(89, 111, 148, 0.5)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{238337df-0b54-41c1-92ac-0d6ebe2a26fc}"
    }
  }
}