LayoutTests/compositing/shared-backing/overflow-scroll/shared-layer-repaint.html

<!DOCTYPE html> <!-- webkit-test-runner [ AsyncOverflowScrollingEnabled=true ] -->
<html>
<head>
    <title>Test repainting with layer sharing</title>
    <style>
        .container {
            position: relative;
            width: 200px;
            height: 200px;
            margin: 50px;
            border: 1px solid black;
            overflow: hidden;
            box-shadow: 0 0 14px gray;
        }
        
        .box {
            width: 100px;
            height: 100px;
            background-color: blue;
            margin: 10px;
        }
        
        .box.changed {
            background-color: orange;
        }
        
        .trigger {
            position: absolute;
            left: 20px;
            top: 10px;
            width: 50px;
            height: 50px;
            background-color: gray;
            transform: translateZ(0);
        }
        
        .relative {
            position: relative;
            top: 50px;
            left: 120px;
            border: 5px solid green;
        }
    </style>
    <script>
        if (window.testRunner) {
            testRunner.dumpAsText();
            testRunner.waitUntilDone();
        }

        window.addEventListener('load', () => {
            setTimeout(() => {
                document.body.offsetTop;
                if (window.internals)
                    window.internals.startTrackingRepaints();

                document.getElementById('target').classList.add('changed');
            
                if (window.internals)
                    document.getElementById('layers').textContent = internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_REPAINT_RECTS);

                if (window.testRunner)
                    testRunner.notifyDone();
            }, 0);
        }, false);
    </script>
</head>
<body>
    <div class="trigger"></div>
    <div class="container">
        <div id="target" class="relative box">
        </div>
    </div>
<pre id="layers"></pre>
</body>
</html>