[layoutng] Cache min/max content size in ComputeInlineSizeForFragment

This also required fixing the relayout when the scrollbar changes, which fixes
css3/flexbox/scrollbars-auto.html (and avoids breaking two tests in
external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox)

Bug: 635619

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I790f0524b029a3c2340b6b9715c5b3529c75357f
Reviewed-on: https://chromium-review.googlesource.com/1162657
Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582464}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -68,7 +68,6 @@ crbug.com/591099 css3/flexbox/bug646288.html [ Failure ]
 crbug.com/591099 css3/flexbox/flex-flow-margins-auto-size.html [ Failure ]
 crbug.com/591099 css3/flexbox/intrinsic-width-orthogonal-writing-mode.html [ Failure ]
 crbug.com/591099 css3/flexbox/line-wrapping.html [ Failure ]
-crbug.com/591099 css3/flexbox/scrollbars-auto.html [ Failure ]
 crbug.com/714962 css3/masking/clip-path-reference-box-inline.html [ Failure ]
 crbug.com/591099 editing/selection/paint-hyphen.html [ Pass ]
 crbug.com/591099 external/wpt/2dcontext/drawing-images-to-the-canvas/drawimage_html_image_11.html [ Pass ]

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

@@ -29,6 +29,7 @@
 #include "third_party/blink/renderer/core/layout/ng/ng_page_layout_algorithm.h"
 #include "third_party/blink/renderer/core/layout/shapes/shape_outside_info.h"
 #include "third_party/blink/renderer/core/paint/paint_layer.h"
+#include "third_party/blink/renderer/core/paint/paint_layer_scrollable_area.h"
 #include "third_party/blink/renderer/platform/runtime_enabled_features.h"
 #include "third_party/blink/renderer/platform/text/writing_mode.h"
 
@@ -241,8 +242,20 @@ scoped_refptr<NGLayoutResult> NGBlockNode::Layout(
     box_->ComputePreferredLogicalWidths();
   }
 
+  bool preferred_logical_widths_were_dirty =
+      box_->PreferredLogicalWidthsDirty();
   layout_result = LayoutWithAlgorithm(*this, constraint_space, break_token,
                                       /* ignored */ nullptr);
+  if (!preferred_logical_widths_were_dirty &&
+      box_->PreferredLogicalWidthsDirty()) {
+    // The only thing that should dirty preferred widths at this point is the
+    // addition of overflow:auto scrollbars in a descendant. To avoid a
+    // potential infinite loop, run layout again with auto scrollbars frozen in
+    // their current state.
+    PaintLayerScrollableArea::FreezeScrollbarsScope freeze_scrollbars;
+    layout_result = LayoutWithAlgorithm(*this, constraint_space, break_token,
+                                        /* ignored */ nullptr);
+  }
   if (block_flow) {
     block_flow->SetCachedLayoutResult(constraint_space, break_token,
                                       layout_result);

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

@@ -430,6 +430,10 @@ LayoutUnit ComputeInlineSizeForFragment(const NGConstraintSpace& space,
     } else {
       min_and_max = node.ComputeMinMaxSize(space.GetWritingMode(),
                                            MinMaxSizeInput(), &space);
+      // Cache these computed values
+      MinMaxSize contribution = ComputeMinAndMaxContentContribution(
+          style.GetWritingMode(), style, min_and_max);
+      box->SetPreferredLogicalWidthsFromNG(contribution);
     }
   }
 

third_party/blink/renderer/core/paint/paint_layer_scrollable_area.cc

@@ -957,46 +957,47 @@ void PaintLayerScrollableArea::UpdateAfterLayout() {
       GetLayoutBox()->GetDocument().SetAnnotatedRegionsDirty(true);
 
     // Our proprietary overflow: overlay value doesn't trigger a layout.
-    // If the box is managed by LayoutNG, don't go here. We don't want to
-    // re-enter the NG layout algorithm for this box from here.
     if (((horizontal_scrollbar_should_change &&
           GetLayoutBox()->StyleRef().OverflowX() != EOverflow::kOverlay) ||
          (vertical_scrollbar_should_change &&
-          GetLayoutBox()->StyleRef().OverflowY() != EOverflow::kOverlay)) &&
-        !IsManagedByLayoutNG(*GetLayoutBox())) {
+          GetLayoutBox()->StyleRef().OverflowY() != EOverflow::kOverlay))) {
       if ((vertical_scrollbar_should_change &&
            GetLayoutBox()->IsHorizontalWritingMode()) ||
           (horizontal_scrollbar_should_change &&
            !GetLayoutBox()->IsHorizontalWritingMode())) {
         GetLayoutBox()->SetPreferredLogicalWidthsDirty();
       }
-      if (PreventRelayoutScope::RelayoutIsPrevented()) {
-        // We're not doing re-layout right now, but we still want to
-        // add the scrollbar to the logical width now, to facilitate parent
-        // layout.
-        GetLayoutBox()->UpdateLogicalWidth();
-        PreventRelayoutScope::SetBoxNeedsLayout(*this, had_horizontal_scrollbar,
-                                                had_vertical_scrollbar);
-      } else {
-        in_overflow_relayout_ = true;
-        SubtreeLayoutScope layout_scope(*GetLayoutBox());
-        layout_scope.SetNeedsLayout(
-            GetLayoutBox(), LayoutInvalidationReason::kScrollbarChanged);
-        if (GetLayoutBox()->IsLayoutBlock()) {
-          LayoutBlock* block = ToLayoutBlock(GetLayoutBox());
-          block->ScrollbarsChanged(horizontal_scrollbar_should_change,
-                                   vertical_scrollbar_should_change);
-          block->UpdateBlockLayout(true);
+      // If the box is managed by LayoutNG, don't go here. We don't want to
+      // re-enter the NG layout algorithm for this box from here.
+      if (!IsManagedByLayoutNG(*GetLayoutBox())) {
+        if (PreventRelayoutScope::RelayoutIsPrevented()) {
+          // We're not doing re-layout right now, but we still want to
+          // add the scrollbar to the logical width now, to facilitate parent
+          // layout.
+          GetLayoutBox()->UpdateLogicalWidth();
+          PreventRelayoutScope::SetBoxNeedsLayout(
+              *this, had_horizontal_scrollbar, had_vertical_scrollbar);
         } else {
-          GetLayoutBox()->UpdateLayout();
+          in_overflow_relayout_ = true;
+          SubtreeLayoutScope layout_scope(*GetLayoutBox());
+          layout_scope.SetNeedsLayout(
+              GetLayoutBox(), LayoutInvalidationReason::kScrollbarChanged);
+          if (GetLayoutBox()->IsLayoutBlock()) {
+            LayoutBlock* block = ToLayoutBlock(GetLayoutBox());
+            block->ScrollbarsChanged(horizontal_scrollbar_should_change,
+                                     vertical_scrollbar_should_change);
+            block->UpdateBlockLayout(true);
+          } else {
+            GetLayoutBox()->UpdateLayout();
+          }
+          in_overflow_relayout_ = false;
+          scrollbar_manager_.DestroyDetachedScrollbars();
+        }
+        LayoutObject* parent = GetLayoutBox()->Parent();
+        if (parent && parent->IsFlexibleBox()) {
+          ToLayoutFlexibleBox(parent)->ClearCachedMainSizeForChild(
+              *GetLayoutBox());
         }
-        in_overflow_relayout_ = false;
-        scrollbar_manager_.DestroyDetachedScrollbars();
-      }
-      LayoutObject* parent = GetLayoutBox()->Parent();
-      if (parent && parent->IsFlexibleBox()) {
-        ToLayoutFlexibleBox(parent)->ClearCachedMainSizeForChild(
-            *GetLayoutBox());
       }
     }
   }