Examine source code of Palette Extractor

{
  "manifest_version": 2,
  "name": "Palette Extractor",
  "version": "1.0",
  "description": "Extrae todos los colores de la hoja de estilos de una página.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ef2cf830-6178-4d5b-9db3-d924a3d0e0e8}"
    }
  }
}