Look recursively for composited scrollers, not just stopping

at the enclosing scrolling ancestor. Bug: 903067 Change-Id: Ice5deb0047862fa72a47e34b1f54f6a6955ae56c Reviewed-on: https://chromium-review.googlesource.com/c/1336784Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org> Commit-Queue: Chris Harrelson <chrishtr@chromium.org> Cr-Commit-Position: refs/heads/master@{#608382}

Look recursively for composited scrollers, not just stopping
at the enclosing scrolling ancestor. Bug: 903067 Change-Id: Ice5deb0047862fa72a47e34b1f54f6a6955ae56c Reviewed-on: https://chromium-review.googlesource.com/c/1336784Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org> Commit-Queue: Chris Harrelson <chrishtr@chromium.org> Cr-Commit-Position: refs/heads/master@{#608382}
4fe211a9 · Chris Harrelson · Commit Bot · c4f56158 · 4fe211a9 · 4fe211a9
Commit 4fe211a9 authored Nov 15, 2018 by Chris Harrelson Committed by Commit Bot Nov 15, 2018
3 changed files
--- a/third_party/WebKit/LayoutTests/compositing/overflow/non-composited-scroll-inside-composited-fixed-position-expected.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/non-composited-scroll-inside-composited-fixed-position-expected.html
+<table style="width: 700px; background: white;">
+  <td style="position: relative">
+    test
+  </td>
+</table>
--- a/third_party/WebKit/LayoutTests/compositing/overflow/non-composited-scroll-inside-composited-fixed-position.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/non-composited-scroll-inside-composited-fixed-position.html
+<!doctype HTML>
+<style>
+::-webkit-scrollbar {
+    display: none;
+}
+</style>
+<div style="position: fixed; overflow: auto;">
+  <div style="height: 700px; position: fixed; overflow: auto;">
+    <div style="height: 900px; position: relative;">
+      <div style="width: 400px; overflow: auto;">
+        <table style="width: 700px; background: white;">
+          <td style="position: relative">
+            test
+          </td>
+        </table>
+      </div>
+    </div>
+  </div>
+</div>
--- a/third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater.cc
+++ b/third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater.cc
@@ -272,11 +272,18 @@ void CompositingRequirementsUpdater::UpdateRecursive(
  CompositingReasons reasons_to_composite = CompositingReason::kNone;
  CompositingReasons direct_reasons = CompositingReason::kNone;
-  bool has_non_root_composited_scrolling_ancestor =
+  bool has_non_root_composited_scrolling_ancestor = false;
-      layer->AncestorScrollingLayer() &&
+  const PaintLayer* ancestor_scrolling_layer = layer->AncestorScrollingLayer();
-      layer->AncestorScrollingLayer()->GetScrollableArea() &&
+  while (ancestor_scrolling_layer &&
-      layer->AncestorScrollingLayer()->NeedsCompositedScrolling() &&
+         ancestor_scrolling_layer->GetScrollableArea()) {
-      !layer->AncestorScrollingLayer()->IsRootLayer();
+    if (ancestor_scrolling_layer->NeedsCompositedScrolling() &&
+        !ancestor_scrolling_layer->IsRootLayer()) {
+      has_non_root_composited_scrolling_ancestor = true;
+      break;
+    }
+    ancestor_scrolling_layer =
+        ancestor_scrolling_layer->AncestorScrollingLayer();
+  }
  bool use_clipped_bounding_rect = !has_non_root_composited_scrolling_ancestor;