[FlexNG] Fix auto scrollbars and scrollable overflow.

In order to get use the correct min/max sizes for flex-items we need
to perform a layout *before* calling ComputeMinMaxSize.

(This is yet another reason why we should merge the min/max sizes pass
 with regular layout).

Additionally this patch implements the:
LayoutBox::HasTopOverflow
LayoutBox::HasLeftOverflow
methods to correctly calculate the scrollable overflow.

Bug: 845235
Change-Id: I3059dfa72969c690abe3808629166194c84fcd75
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1978103
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: David Grogan <dgrogan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728071}

third_party/blink/renderer/core/layout/ng/layout_ng_flexible_box.cc

@@ -17,6 +17,21 @@ namespace blink {
 LayoutNGFlexibleBox::LayoutNGFlexibleBox(Element* element)
     : LayoutNGMixin<LayoutBlock>(element) {}
 
+bool LayoutNGFlexibleBox::HasTopOverflow() const {
+  if (IsHorizontalWritingMode())
+    return StyleRef().ResolvedIsColumnReverseFlexDirection();
+  return StyleRef().IsLeftToRightDirection() ==
+         StyleRef().ResolvedIsRowReverseFlexDirection();
+}
+
+bool LayoutNGFlexibleBox::HasLeftOverflow() const {
+  if (IsHorizontalWritingMode()) {
+    return StyleRef().IsLeftToRightDirection() ==
+           StyleRef().ResolvedIsRowReverseFlexDirection();
+  }
+  return StyleRef().ResolvedIsColumnReverseFlexDirection();
+}
+
 void LayoutNGFlexibleBox::UpdateBlockLayout(bool relayout_children) {
   LayoutAnalyzer::BlockScope analyzer(*this);
 

third_party/blink/renderer/core/layout/ng/layout_ng_flexible_box.h

@@ -15,6 +15,9 @@ class CORE_EXPORT LayoutNGFlexibleBox : public LayoutNGMixin<LayoutBlock> {
  public:
   explicit LayoutNGFlexibleBox(Element*);
 
+  bool HasTopOverflow() const override;
+  bool HasLeftOverflow() const override;
+
   void UpdateBlockLayout(bool relayout_children) override;
 
   bool IsFlexibleBoxIncludingDeprecatedAndNG() const final { return true; }

third_party/blink/renderer/core/layout/ng/ng_flex_layout_algorithm.cc

@@ -345,18 +345,22 @@ void NGFlexLayoutAlgorithm::ConstructAndAppendFlexItems() {
         is_horizontal_flow_ ? physical_border_scrollbar_padding.HorizontalSum()
                             : physical_border_scrollbar_padding.VerticalSum();
 
+    // TODO(dgrogan): Don't layout every time, just when you need to.
+    // Use ChildHasIntrinsicMainAxisSize as a guide.
+    scoped_refptr<const NGLayoutResult> layout_result =
+        child.Layout(child_space, /* break_token */ nullptr);
+    NGFragment fragment_in_child_writing_mode(
+        child_style.GetWritingMode(), layout_result->PhysicalFragment());
+
     // We want the child's min/max size in its writing mode, not ours. We'll
     // only ever use it if the child's inline axis is our main axis.
+    //
+    // Always calculate the min/max sizes after a layout in order to corrrectly
+    // account for any scrollbars.
     MinMaxSizeInput input(
         /* percentage_resolution_block_size */ content_box_size_.block_size);
     MinMaxSize intrinsic_sizes_border_box = child.ComputeMinMaxSize(
         child_style.GetWritingMode(), input, &child_space);
-    // TODO(dgrogan): Don't layout every time, just when you need to.
-    // Use ChildHasIntrinsicMainAxisSize as a guide.
-    scoped_refptr<const NGLayoutResult> layout_result =
-        child.Layout(child_space, nullptr /*break token*/);
-    NGFragment fragment_in_child_writing_mode(
-        child_style.GetWritingMode(), layout_result->PhysicalFragment());
 
     LayoutUnit flex_base_border_box;
     const Length& specified_length_in_main_axis =

third_party/blink/web_tests/TestExpectations

@@ -1308,7 +1308,6 @@ crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-align-vertical-wri
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flex-align.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flexbox-baseline-margins.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flexbox-baseline.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/flexbox-overflow-auto.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/minimum-size-image.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/multiline-reverse-wrap-baseline.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/css3/flexbox/negative-overflow.html [ Failure ]
@@ -1340,8 +1339,6 @@ crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/overflo
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/percentage-heights-007.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/percentage-heights-quirks-node.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/quirks-auto-block-size-with-percentage-item.html [ Pass Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/scrollbars-auto.html [ Failure ]
-crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/scrollbars.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/table-as-item-auto-min-width.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/ttwf-reftest-flex-inline.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_flex_box/external/wpt/css/css-flexbox/hittest-overlapping-margin.html [ Failure ]