third_party/WebKit/LayoutTests/fast/canvas/canvas-toBlob-toDataURL-race-imageEncoder-png.html

<script src = "../../resources/js-test.js"></script>
<script src = "./script-tests/canvas-toBlob-toDataURL-race.js"></script>
<script type = 'text/javascript'>
description("Verifies if PNG image encoding on main thread (toDataURL) conflicts with image encoding on async thread (toBlob)");

//Fire a bunch of toBlob operations of canvas to keep the async thread busy
var j = 0; // due to async nature of toBlob we need a separate counter
for (var i = 0; i < numToBlobCalls; i++) 
{
    canvas.toBlob(function(blob) {
        url = URL.createObjectURL(blob);
        testImages[j++].src = url;
    });
}

//Then file a bunch of toDataURL operation on main thread, so both threads now compete for image encoding
for (var i = numToBlobCalls; i < (numToDataURLCalls + numToBlobCalls); i++) 
{
    testImages[i].src = canvas.toDataURL();
}
</script>