chrome/browser/resources/welcome/shared/step_indicator.html

<style include="navi-colors-css">
  :host {
    align-items: center;
    display: flex;
  }

  span {
    background: var(--navi-step-indicator-color);
    border-radius: 50%;
    display: inline-block;
    height: 8px;
    margin: 0 4px;
    width: 8px;
  }

  span.active {
    background: var(--navi-step-indicator-active-color);
  }
</style>
<template is="dom-repeat" items="[[dots_]]">
  <span class$="[[getActiveClass_(index, model.active)]]"></span>
</template>