chrome/browser/resources/print_preview/ui/throbber_css.html

<template>
  <style>
    .throbber {
      background: url(chrome://resources/images/throbber_small.svg) no-repeat;
      display: inline-block;
      height: var(--throbber-size);
      width: var(--throbber-size);
    }
  </style>
</template>