chromium/third_party/blink/web_tests/fast/hidpi/image-srcset-simple-2x.html

<!DOCTYPE html>
<script>
    window.targetScaleFactor = 2;
</script>
<script src="resources/srcset-helper.js"></script>
<script src="../../resources/js-test.js"></script>
<script>
    addEventListener("load", function() {
        shouldBeTrue('document.getElementById("foo").clientWidth==200');
    }, false);
</script>
<div>This test passes if the image below says 1x with a reddish background when the deviceScaleFactor is 1, and if says 2x with a greenish background when the deviceScaleFactor is 2.</div>
<img id="foo" src="" srcset="resources/blue-100-px-square.png 1x, resources/deleteButton.png 3x, resources/green-400-px-square.png 2x">