chromium/src/third_party/blink/web_tests/paint/invalidation/resources/window-resize-repaint.js

var testSizes = [
    { width: 600, height: 500 }, // initial size
    { width: 600, height: 250 }, // height decrease
    { width: 400, height: 250 }, // width decrease
    { width: 400, height: 600 }, // height increase
    { width: 800, height: 600 }  // width increase
];

var sizeIndex = 0;
var repaintRects = "";

if (window.internals)
    internals.runtimeFlags.paintUnderInvalidationCheckingEnabled = true;

function doTest() {
    if (sizeIndex) {
        repaintRects += internals.layerTreeAsText(document, window.internals.LAYER_TREE_INCLUDES_INVALIDATIONS);
        internals.stopTrackingRepaints(document);
    }
    ++sizeIndex;
    if (sizeIndex < testSizes.length) {
        internals.startTrackingRepaints(document);
        window.resizeTo(testSizes[sizeIndex].width, testSizes[sizeIndex].height);
        runAfterLayoutAndPaint(doTest);
    } else if (window.testRunner) {
        testRunner.setCustomTextOutput(repaintRects);
        testRunner.notifyDone();
    }
}

if (window.testRunner) {
    testRunner.useUnfortunateSynchronousResizeMode();
    testRunner.waitUntilDone();
    onload = function() {
        window.resizeTo(testSizes[0].width, testSizes[0].height);
        runAfterLayoutAndPaint(doTest);
    };
}