third_party/blink/web_tests/svg/custom/pattern-directly-and-indirectly-referenced.svg

<svg xmlns="http://www.w3.org/2000/svg">
  <pattern width="100%" height="100%" id="pattern" viewBox="0 0 100 100">
    <rect width="100" height="100" fill="gray"/>
  </pattern>
  <mask id="mask">
    <circle fill="url(#pattern)" cx="100" cy="100" r="100"/>
  </mask>
  <rect width="200" height="200" mask="url(#mask)" fill="url(#pattern)"/>
</svg>