Ensure nested scrollers clip contents.

When painting composited overflow, kPaintLayerPaintingOverflowContents is set to paint all content. When painting a nested, transformed scroller, we need to ensure this flag is unset so the contents are clipped. Because root layer scrolling (RLS) paints the root layer as a regular overflow scroller, this bug affected more tests with RLS. With this patch, 5 more tests pass with root layer scrolling. Bug: 779885 Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2 Change-Id: I311cfa9e3244192b24ec3dd566aa2c65e9dba851 Reviewed-on: https://chromium-review.googlesource.com/748081 Commit-Queue: Philip Rogers <pdr@chromium.org> Reviewed-by: Tien-Ren Chen <trchen@chromium.org> Cr-Commit-Position: refs/heads/master@{#513045}

Ensure nested scrollers clip contents.
When painting composited overflow, kPaintLayerPaintingOverflowContents is set to paint all content. When painting a nested, transformed scroller, we need to ensure this flag is unset so the contents are clipped. Because root layer scrolling (RLS) paints the root layer as a regular overflow scroller, this bug affected more tests with RLS. With this patch, 5 more tests pass with root layer scrolling. Bug: 779885 Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2 Change-Id: I311cfa9e3244192b24ec3dd566aa2c65e9dba851 Reviewed-on: https://chromium-review.googlesource.com/748081 Commit-Queue: Philip Rogers <pdr@chromium.org> Reviewed-by: Tien-Ren Chen <trchen@chromium.org> Cr-Commit-Position: refs/heads/master@{#513045}
19f7cb8a · Philip Rogers · Commit Bot · 99779b65 · 19f7cb8a · 19f7cb8a
Commit 19f7cb8a authored Nov 01, 2017 by Philip Rogers Committed by Commit Bot Nov 01, 2017
4 changed files
--- a/third_party/WebKit/LayoutTests/FlagExpectations/root-layer-scrolls
+++ b/third_party/WebKit/LayoutTests/FlagExpectations/root-layer-scrolls
@@ -30,11 +30,9 @@ crbug.com/417782 compositing/squashing/squash-above-fixed-1.html [ Failure ]
 crbug.com/417782 compositing/squashing/squash-above-fixed-3.html [ Failure ]
 crbug.com/417782 compositing/squashing/squashing-print.html [ Failure ]
 crbug.com/417782 compositing/visibility/visibility-image-layers-dynamic.html [ Failure ]
-crbug.com/417782 css3/filters/nested-filter.html [ Failure ]
 crbug.com/417782 editing/input/scroll-viewport-page-up-down.html [ Failure ]
 crbug.com/417782 external/wpt/css/css-position-3/position-sticky-root-scroller.html [ Failure ]
 crbug.com/417782 [ Mac ] fast/body-propagation/background-image/007.html [ Failure ]
-crbug.com/417782 fast/css/resize-corner-tracking-transformed.html [ Failure ]
 crbug.com/417782 fast/css/sticky/replaced-sticky.html [ Failure ]
 crbug.com/417782 fast/css/sticky/sticky-style-change.html [ Failure ]
 crbug.com/417782 fast/css/zoom-body-scroll.html [ Failure ]
@@ -61,7 +59,6 @@ crbug.com/417782 [ Linux Win ] fast/forms/placeholder-position.html [ Failure ]
 crbug.com/417782 [ Linux Win ] fast/forms/select-popup/popup-menu-appearance-transform.html [ Failure ]
 crbug.com/417782 fast/frames/iframe-scaling-with-scroll.html [ Failure ]
 crbug.com/417782 fast/layers/scroll-rect-to-visible.html [ Failure ]
-crbug.com/417782 fast/layers/scroll-with-transform-layer.html [ Failure ]
 crbug.com/417782 fast/layout/scroll-anchoring/history-restore-anchors.html [ Failure ]
 crbug.com/417782 fast/loader/scroll-position-restoration-without-premature-clamping.html [ Failure ]
 crbug.com/417782 fast/loader/scroll-position-restored-on-back-at-load-event.html [ Failure ]
@@ -105,7 +102,6 @@ crbug.com/417782 paint/invalidation/media-audio-no-spurious-repaints.html [ Fail
 crbug.com/417782 paint/invalidation/overflow-scroll-body-appear.html [ Failure ]
 crbug.com/417782 paint/invalidation/positioned-document-element.html [ Crash ]
 crbug.com/417782 paint/invalidation/resize-iframe-text.html [ Failure ]
-crbug.com/417782 paint/invalidation/scroll-in-transformed-layer.html [ Failure ]
 crbug.com/417782 paint/invalidation/subpixel-shadow-included-in-invalidation.html [ Failure ]
 crbug.com/417782 paint/invalidation/svg/absolute-sized-document-no-scrollbars.svg [ Failure ]
 crbug.com/417782 paint/invalidation/svg/deep-nested-embedded-svg-size-changes-no-layout-triggers-1.html [ Failure ]
@@ -140,7 +136,6 @@ crbug.com/417782 printing/thead-repeats-at-top-of-each-page.html [ Failure ]
 crbug.com/417782 svg/W3C-SVG-1.1/masking-path-04-b.svg [ Failure ]
 crbug.com/417782 svg/custom/mask-with-default-value.svg [ Failure ]
 crbug.com/417782 [ Mac ] svg/custom/masking-clipping-hidpi.svg [ Failure ]
-crbug.com/417782 transforms/overflow-with-transform.html [ Failure ]
 crbug.com/417782 transforms/selection-bounds-in-transformed-view.html [ Failure ]
 crbug.com/417782 [ Linux ] virtual/android/fast/rootscroller/browser-controls-background-iframe.html [ Failure ]
 crbug.com/417782 [ Linux ] virtual/android/fast/rootscroller/browser-controls-gradient-background-iframe-scroller.html [ Failure ]

--- a/third_party/WebKit/LayoutTests/compositing/overflow/nested-overflow-clip-expected.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/nested-overflow-clip-expected.html
+<!doctype html>
+This test passes if there is no red.
--- a/third_party/WebKit/LayoutTests/compositing/overflow/nested-overflow-clip.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/nested-overflow-clip.html
+<!doctype html>
+<style>
+  ::-webkit-scrollbar {
+    display: none;
+  }
+</style>
+This test passes if there is no red.
+<div id="scroller" style="position: absolute; width: 400px; height: 400px; overflow-y: scroll; will-change: transform;">
+  <div id="transformed" style="width: 100px; height: 100px; top: 100px; left: 50px; position: absolute; overflow: hidden; transform: rotate(45deg);">
+    <!-- This rect should be entirely clipped out. -->
+    <div style="width: 100px; height: 100px; top: 100px; left: 50px; position: absolute; background: red;"></div>
+  </div>
+  <div id="forcescroll" style="height: 1000px;"></div>
+</div>
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -853,9 +853,12 @@ PaintResult PaintLayerPainter::PaintFragmentByApplyingTransform(
  transformed_painting_info.ancestor_has_clip_path_clipping =
      painting_info.ancestor_has_clip_path_clipping;
-  // Remove skip root background flag when we're painting with a new root.
+  if (&paint_layer_ != painting_info.root_layer) {
-  if (&paint_layer_ != painting_info.root_layer)
+    // Remove skip root background flag when we're painting with a new root.
    paint_flags &= ~kPaintLayerPaintingSkipRootBackground;
+    // When painting a new root we are no longer painting overflow contents.
+    paint_flags &= ~kPaintLayerPaintingOverflowContents;
+  }
  return PaintLayerContentsCompositingAllPhases(
      context, transformed_painting_info, paint_flags, kForceSingleFragment);