[css-grid] Preemptively store intrinsic sizes during layout

third_party/WebKit/Source/core/layout/LayoutGrid.cpp

Index: third_party/WebKit/Source/core/layout/LayoutGrid.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
index 957ecad4da47dc281d667cbd7d469519da0556cd..5ad5e7298be7466e0ef7603db0a487b01f7670cc 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -265,6 +265,22 @@ void LayoutGrid::UpdateBlockLayout(bool relayout_children) {
     LayoutUnit available_space_for_columns = AvailableLogicalWidth();
     ComputeTrackSizesForDefiniteSize(kForColumns, available_space_for_columns);
 
+    // We take the chance to store the intrinsic sizes as they are just an
+    // intermediate result of the track sizing algorithm. Apart from eventually
+    // saving an algorithm execution (if {min|max}PreferredLogicalWidth() are
+    // called later), it fixes the use case of computing the preferred logical
+    // widths *after* the layout process. Although not very common, this happens
+    // in the Mac (content::RenderViewImpl::didUpdateLayout()) or under some
+    // circumstances when grids are also flex items (crbug.com/708159).
+    if (PreferredLogicalWidthsDirty()) {
+      LayoutUnit scrollbar_width = LayoutUnit(ScrollbarLogicalWidth());
+      min_preferred_logical_width_ =
+          track_sizing_algorithm_.MinContentSize() + scrollbar_width;
+      max_preferred_logical_width_ =
+          track_sizing_algorithm_.MaxContentSize() + scrollbar_width;
+      ClearPreferredLogicalWidthsDirty();
+    }
+
     // 2- Next, the track sizing algorithm resolves the sizes of the grid rows,
     // using the grid column sizes calculated in the previous step.
     if (CachedHasDefiniteLogicalHeight()) {