Call SetNeedsAssignmentRecalc in HTMLSlotElement::ChildrenChanged

(cherry picked from commit 3f7c402) Bug: 1184357 Change-Id: Id9e804e5762ac6c40ba1be0620401d219d6f4d90 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2734104 Commit-Queue: Joey Arhar <jarhar@chromium.org> Reviewed-by: Mason Freed <masonfreed@chromium.org> Cr-Original-Commit-Position: refs/heads/master@{#859652} Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2734255 Reviewed-by: Krishna Govind <govind@chromium.org> Cr-Commit-Position: refs/branch-heads/4435@{#5} Cr-Branched-From: f3c257e-refs/heads/master@{#859168}
chromium · Mar 4, 2021 · 7610baf · 7610baf
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commit 7610baf
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diff --git a/third_party/blink/renderer/core/html/html_slot_element.cc b/third_party/blink/renderer/core/html/html_slot_element.cc
@@ -758,6 +758,12 @@ bool HTMLSlotElement::HasAssignedNodesSlow() const {
   return assignment.FindHostChildBySlotName(GetName());
 }
 
+void HTMLSlotElement::ChildrenChanged(const ChildrenChange& change) {
+  Element::ChildrenChanged(change);
+  if (SupportsAssignment())
+    SetShadowRootNeedsAssignmentRecalc();
+}
+
 void HTMLSlotElement::Trace(Visitor* visitor) const {
   visitor->Trace(assigned_nodes_);
   visitor->Trace(flat_tree_children_);

diff --git a/third_party/blink/renderer/core/html/html_slot_element.h b/third_party/blink/renderer/core/html/html_slot_element.h
@@ -125,6 +125,8 @@ class CORE_EXPORT HTMLSlotElement final : public HTMLElement {
   InsertionNotificationRequest InsertedInto(ContainerNode&) final;
   void RemovedFrom(ContainerNode&) final;
 
+  void ChildrenChanged(const ChildrenChange&) override;
+
   void EnqueueSlotChangeEvent();
 
   bool HasSlotableChild() const;

diff --git a/third_party/blink/web_tests/external/wpt/dom/slot-recalc-ref.html b/third_party/blink/web_tests/external/wpt/dom/slot-recalc-ref.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<div>
+  <p>there should be more text below this</p>
+  <p>PASS if this text is visible</p>
+</div>
diff --git a/third_party/blink/web_tests/external/wpt/dom/slot-recalc.html b/third_party/blink/web_tests/external/wpt/dom/slot-recalc.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<link rel="author" title="Joey Arhar" href="mailto:jarhar@chromium.org">
+<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1184357">
+
+<link rel="match" href="/dom/slot-recalc-ref.html">
+
+<body>
+<script>
+const host = document.createElement('div');
+document.body.appendChild(host);
+const root = host.attachShadow({mode: 'open'});
+
+const slot = document.createElement('slot');
+slot.innerHTML = `<p>there should be more text below this</p>`;
+root.appendChild(slot);
+
+onload = () => {
+  const shouldBeVisible = document.createElement('p');
+  shouldBeVisible.textContent = 'PASS if this text is visible';
+  slot.appendChild(shouldBeVisible);
+};
+</script>