chrome/content/img/loading-bars.svg

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" width="32" height="32" fill="white">
  <path transform="translate(2)" d="M0 12 V20 H4 V12z"> 
    <animate attributeName="d" values="M0 12 V20 H4 V12z; M0 4 V28 H4 V4z; M0 12 V20 H4 V12z; M0 12 V20 H4 V12z" dur="1.2s" repeatCount="indefinite" begin="0" keytimes="0;.2;.5;1" keySplines="0.2 0.2 0.4 0.8;0.2 0.6 0.4 0.8;0.2 0.8 0.4 0.8" calcMode="spline"  />
  </path>
  <path transform="translate(8)" d="M0 12 V20 H4 V12z">
    <animate attributeName="d" values="M0 12 V20 H4 V12z; M0 4 V28 H4 V4z; M0 12 V20 H4 V12z; M0 12 V20 H4 V12z" dur="1.2s" repeatCount="indefinite" begin="0.2" keytimes="0;.2;.5;1" keySplines="0.2 0.2 0.4 0.8;0.2 0.6 0.4 0.8;0.2 0.8 0.4 0.8" calcMode="spline"  />
  </path>
  <path transform="translate(14)" d="M0 12 V20 H4 V12z">
    <animate attributeName="d" values="M0 12 V20 H4 V12z; M0 4 V28 H4 V4z; M0 12 V20 H4 V12z; M0 12 V20 H4 V12z" dur="1.2s" repeatCount="indefinite" begin="0.4" keytimes="0;.2;.5;1" keySplines="0.2 0.2 0.4 0.8;0.2 0.6 0.4 0.8;0.2 0.8 0.4 0.8" calcMode="spline" />
  </path>
  <path transform="translate(20)" d="M0 12 V20 H4 V12z">
    <animate attributeName="d" values="M0 12 V20 H4 V12z; M0 4 V28 H4 V4z; M0 12 V20 H4 V12z; M0 12 V20 H4 V12z" dur="1.2s" repeatCount="indefinite" begin="0.6" keytimes="0;.2;.5;1" keySplines="0.2 0.2 0.4 0.8;0.2 0.6 0.4 0.8;0.2 0.8 0.4 0.8" calcMode="spline" />
  </path>
  <path transform="translate(26)" d="M0 12 V20 H4 V12z">
    <animate attributeName="d" values="M0 12 V20 H4 V12z; M0 4 V28 H4 V4z; M0 12 V20 H4 V12z; M0 12 V20 H4 V12z" dur="1.2s" repeatCount="indefinite" begin="0.8" keytimes="0;.2;.5;1" keySplines="0.2 0.2 0.4 0.8;0.2 0.6 0.4 0.8;0.2 0.8 0.4 0.8" calcMode="spline" />
  </path>
</svg>