chromium/ui/file_manager/file_manager/foreground/images/common/drag_drop_allow.svg

<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20">
  <path fill="#fff" d="M11 4v5h5v2h-5v5H9v-5H4V9h5V4h2z"/>
</svg>