Examine source code of (1900 × 50 px)

{
  "name": "(1900 × 50 px)",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "(1900 × 50 px).jpg"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b4edd038-3f23-4e84-bc71-9a3e3f65cc55}"
    }
  }
}