chromium/content/test/data/gpu/pixel_webgpu_copy_externalImage_2d_canvas.html

<!DOCTYPE html>
<html>
<head>
  <title>WebGPU copyExternalImageToTexture test</title>
  <style type="text/css">
  .nomargin {
    margin: 0px auto;
  }
  </style>
  <script type="text/javascript" src="pixel_webgpu_util.js"></script>
  <script type="text/javascript">
    var g_swapsBeforeAck = 15;

    async function main() {
      const canvas2d = document.getElementById('canvas_2d');
      const c2d = canvas2d.getContext("2d");
      if (!c2d) {
        console.error('getContext(2d) failed');
        return null;
      }

      const gpuCanvas = document.getElementById('canvas_gpu');
      const [gpuDevice, gpuContext] = await webGpuUtils.init(gpuCanvas);
      if (!gpuDevice || !gpuContext) {
        console.error("Failed to initialize WebGPU - skipping test");
        domAutomationController.send("FAILURE");
        return;
      }

      const renderCallback = function() {
        c2d.fillStyle = "rgb(0, 255, 0)";
        c2d.fillRect(0, 0, 100, 100);

        c2d.fillStyle = "rgb(255, 0, 0)";
        c2d.fillRect(0, 100, 100, 100);

        c2d.fillStyle = "rgb(255, 255, 0)";
        c2d.fillRect(100, 100, 100, 100);

        c2d.fillStyle = "rgb(0, 0, 255)";
        c2d.fillRect(100, 0, 100, 100);

        webGpuUtils.uploadToGPUTextureTest(gpuDevice, gpuContext, canvas2d);

        waitForFinish();
      };

      window.requestAnimationFrame(renderCallback);
    }

    function waitForFinish() {
      if (g_swapsBeforeAck == 0) {
        domAutomationController.send("SUCCESS");
      } else {
        g_swapsBeforeAck--;
        window.requestAnimationFrame(waitForFinish);
      }
    }
  </script>
</head>
<body onload="main()">
  <canvas id="canvas_2d" width="200" height="200" class="nomargin"></canvas>
  <canvas id="canvas_gpu" width="200" height="200" class="nomargin"></canvas>
</body>
</html>