[LayoutShiftTracker] Fix contain:paint

We should check ShouldClipOverflow() instead of IsScrollContainer() (which was renamed from HasOverflowClip() recently -- this CL shows how the new name improved code readability) for inclusion of layout overflow for layout shift tracking. Bug: 1127474 Change-Id: Id85b292b65dae837d1e366d548939b85c9cd5d5b Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2417061 Reviewed-by: Nicolás Peña Moreno <npm@chromium.org> Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org> Cr-Commit-Position: refs/heads/master@{#808087}
web-platform-tests · Sep 17, 2020 · fb7851d · fb7851d
1 parent 80c4b6a
commit fb7851d
Showing 1 changed file with 26 additions and 0 deletions.
diff --git a/layout-instability/contain-paint-fully-clipped.html b/layout-instability/contain-paint-fully-clipped.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<title>Layout Instability: fully clipped by contain:paint</title>
+<link rel="help" href="https://wicg.github.io/layout-instability/" />
+<div style="contain: paint; height: 0; position: relative">
+  <div id="target" style="position: absolute; top: 0; width: 400px; height: 400px"></div>
+</div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/util.js"></script>
+<script>
+
+promise_test(async () => {
+  const watcher = new ScoreWatcher;
+
+  // Wait for the initial render to complete.
+  await waitForAnimationFrames(2);
+
+  // Shift target, for which no shift should be reported because it's hidden.
+  document.querySelector("#target").style.top = '200px';
+
+  await waitForAnimationFrames(2);
+  // No shift should be reported.
+  assert_equals(watcher.score, 0);
+}, 'fully clipped by contain:paint');
+
+</script>