Examine source code of Generador de Letras

{
  "manifest_version": 2,
  "name": "Generador de Letras",
  "version": "1.0",
  "description": "Generador de letras para personalizar tus textos",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5b74d88c-12b1-488e-9f10-1212e4c9d8ee}"
    }
  }
}