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chromium/content/test/data/accessibility/aria/toggle-button-expand-collapse.html 

<!--
@BLINK-ALLOW:collapsed*
@BLINK-ALLOW:expanded*
@WIN-ALLOW:PRESSED
@WIN-ALLOW:MIXED
@WIN-ALLOW:checkable:true
-->
<!DOCTYPE html>
<html>
<body>
  <div role="button" aria-pressed="true" aria-expanded="false" aria-haspopup="true">Toggle button, pressed, collapsed</div>
  <div role="button" aria-pressed="false" aria-expanded="false" aria-haspopup="true">Toggle button, not pressed, collapsed</div>
  <div role="button" aria-pressed="true" aria-expanded="true" aria-haspopup="true">Toggle button, pressed, expanded</div>
  <div role="button" aria-pressed="false" aria-expanded="true" aria-haspopup="true">Toggle button, not pressed, collapsed"</div>
</body>
</html>