chromium/chrome/browser/resources/chromeos/healthd_internals/pages/generic_chart.html

<style include="healthd-internals-shared">
  .line-chart-header {
    height: 25px;
  }

  #lineChart {
    display: flex;
    height: calc(100% - 25px);
    width: 100%;
  }
</style>
<div class="full-page">
  <h1 class="line-chart-header">[[chartHeader]]</h1>
  <healthd-internals-line-chart id="lineChart">
  </healthd-internals-line-chart>
</div>