Ensure negative z index children are painted in scrollers

[1] ensured kPaintLayerPaintingOverflowContents was cleared when painting a new root but failed to clear kPaintLayerPaintingCompositingScrollingPhase as well. This caused a regression where negative z index children of a scrolled and transformed paint layer would not paint. This patch fixes and tests the regression from [1], as well as passing one additional test with root layer scrolling. [1] https://crrev.com/19f7cb8adfd015bef06b08d0c02eb5a528e8c885 Bug: 779885 Change-Id: Id73ae360000efe866fd9c9c7c1dade186d547cac Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2 Reviewed-on: https://chromium-review.googlesource.com/749059Reviewed-by: Tien-Ren Chen <trchen@chromium.org> Commit-Queue: Philip Rogers <pdr@chromium.org> Cr-Commit-Position: refs/heads/master@{#513276}

Ensure negative z index children are painted in scrollers
[1] ensured kPaintLayerPaintingOverflowContents was cleared when painting a new root but failed to clear kPaintLayerPaintingCompositingScrollingPhase as well. This caused a regression where negative z index children of a scrolled and transformed paint layer would not paint. This patch fixes and tests the regression from [1], as well as passing one additional test with root layer scrolling. [1] https://crrev.com/19f7cb8adfd015bef06b08d0c02eb5a528e8c885 Bug: 779885 Change-Id: Id73ae360000efe866fd9c9c7c1dade186d547cac Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2 Reviewed-on: https://chromium-review.googlesource.com/749059Reviewed-by: Tien-Ren Chen <trchen@chromium.org> Commit-Queue: Philip Rogers <pdr@chromium.org> Cr-Commit-Position: refs/heads/master@{#513276}
4646c300 · Philip Rogers · Commit Bot · fe47ac22 · 4646c300 · 4646c300
Commit 4646c300 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
@@ -193,7 +193,6 @@ crbug.com/417782 paint/invalidation/caret-subpixel.html [ Failure ]
 crbug.com/417782 paint/invalidation/caret-with-composited-scroll.html [ Failure ]
 crbug.com/417782 paint/invalidation/change-text-content-and-background-color.html [ Failure ]
 crbug.com/417782 paint/invalidation/details-open-repaint.html [ Failure ]
-crbug.com/417782 paint/invalidation/fixed-child-of-transformed-move-after-scroll.html [ Failure ]
 crbug.com/417782 paint/invalidation/invalidate-caret-in-composited-scrolling-container.html [ Failure ]
 crbug.com/417782 paint/invalidation/invalidate-caret-in-non-composited-scrolling-container.html [ Failure ]
 crbug.com/417782 paint/invalidation/multi-layout-one-frame.html [ Failure ]

--- a/third_party/WebKit/LayoutTests/compositing/overflow/overflow-with-negative-z-index-child-expected.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/overflow-with-negative-z-index-child-expected.html
+<!doctype html>
+This test passes if there is a green box.
+<div style="width: 100px; height: 100px; background: green;"></div>
--- a/third_party/WebKit/LayoutTests/compositing/overflow/overflow-with-negative-z-index-child.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/overflow-with-negative-z-index-child.html
+<!doctype html>
+<style>
+  ::-webkit-scrollbar {
+    display: none;
+  }
+  #scroller {
+    position: absolute;
+    width: 400px;
+    height: 400px;
+    overflow-y: scroll;
+    will-change: transform;
+  }
+  #container {
+    transform: translate(0, 0);
+  }
+  #rect {
+    width: 100px;
+    height: 100px;
+    background: green;
+    position: absolute;
+    z-index: -5;
+  }
+</style>
+This test passes if there is a green box.
+<div id="scroller">
+  <div id="container">
+    <div id="rect"></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
@@ -858,6 +858,7 @@ PaintResult PaintLayerPainter::PaintFragmentByApplyingTransform(
    paint_flags &= ~kPaintLayerPaintingSkipRootBackground;
    // When painting a new root we are no longer painting overflow contents.
    paint_flags &= ~kPaintLayerPaintingOverflowContents;
+    paint_flags &= ~kPaintLayerPaintingCompositingScrollingPhase;
  }

  return PaintLayerContentsCompositingAllPhases(