chromium/content/test/data/gpu/pixel_canvas_low_latency_2d.html

<!DOCTYPE HTML>
<html>
<head>
<title>Low Latency Canvas 2D Test: Green and blue box, over large red box, over black</title>
<style type="text/css">
.nomargin {
  margin: 0px auto;
}
</style>
<script>
let g_swapsBeforeAck = 15;
let g_canvas;
let g_c2d;

function main()
{
  g_canvas = document.getElementById("c");
  g_c2d = g_canvas.getContext("2d", {desynchronized: true});
  draw();
}

function draw()
{
  g_c2d.clearRect(0, 0, g_canvas.width, g_canvas.height);
  g_c2d.fillStyle = "red";
  g_c2d.fillRect(10, 10, 80, 80);
  requestAnimationFrame(draw2);
}

function draw2()
{
  // Verify that incremental painting works.
  g_c2d.fillStyle = "green";
  g_c2d.fillRect(20, 20, 30, 30);
  // Verify that output doesn't get flipped vertically.
  g_c2d.fillStyle = "blue";
  g_c2d.fillRect(50, 50, 30, 30);
  waitForFinish();
}

function waitForFinish()
{
  if (g_swapsBeforeAck == 0) {
    domAutomationController.send("SUCCESS");
  } else {
    g_swapsBeforeAck--;
    window.requestAnimationFrame(waitForFinish);
  }
}
</script>
</head>
<body onload="main()" class="nomargin">
<canvas id="c" width="100" height="100" class="nomargin" style="background-color:black"></canvas>
</body>
</html>