[css-grid] Remove the 2x computation of row sizes w/ indefinite heights

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

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 435 matching lines @@
     SubtreeLayoutScope layoutScope(*this);
 
     {
         // LayoutState needs this deliberate scope to pop before updating scroll information (which
         // may trigger relayout).
         LayoutState state(*this, locationOffset());
 
         LayoutSize previousSize = size();
 
         updateLogicalWidth();
-        bool logicalHeightWasIndefinite = !hasDefiniteLogicalHeight();
 
         TextAutosizer::LayoutScope textAutosizerLayoutScope(this, &layoutScope);
 
         // TODO(svillar): we won't need to do this once the intrinsic width computation is isolated
         // from the LayoutGrid object state (it should not touch any attribute) (see crbug.com/627812)
         if (m_autoRepeatColumns && m_autoRepeatColumns != computeAutoRepeatTracksCount(ForColumns, TrackSizing))
             dirtyGrid();
         placeItemsOnGrid(TrackSizing);
 
         GridSizingData sizingData(gridColumnCount(), gridRowCount());
 
         // 1- First, the track sizing algorithm is used to resolve the sizes of the grid columns.
         // At this point the logical width is always definite as the above call to updateLogicalWidth()
         // properly resolves intrinsic sizes. We cannot do the same for heights though because many code
         // paths inside updateLogicalHeight() require a previous call to setLogicalHeight() to resolve
         // heights properly (like for positioned items for example).
         LayoutUnit availableSpaceForColumns = availableLogicalWidth();
         computeTrackSizesForDirection(ForColumns, sizingData, availableSpaceForColumns);
 
         // 2- Next, the track sizing algorithm resolves the sizes of the grid rows, using the
         // grid column sizes calculated in the previous step.
-        if (logicalHeightWasIndefinite)
+        if (!hasDefiniteLogicalHeight())
             computeIntrinsicLogicalHeight(sizingData);
         else
             computeTrackSizesForDirection(ForRows, sizingData, availableLogicalHeight(ExcludeMarginBorderPadding));
         setLogicalHeight(computeTrackBasedLogicalHeight(sizingData) + borderAndPaddingLogicalHeight() + scrollbarLogicalHeight());
 
         LayoutUnit oldClientAfterEdge = clientLogicalBottom();
         updateLogicalHeight();
 
-        // The above call might have changed the grid's logical height depending on min|max height restrictions.
-        // Update the sizes of the rows whose size depends on the logical height (also on definite|indefinite sizes).
-        LayoutUnit availableSpaceForRows = contentLogicalHeight();
-        if (logicalHeightWasIndefinite)
-            computeTrackSizesForDirection(ForRows, sizingData, availableSpaceForRows);
-
         // 3- If the min-content contribution of any grid items have changed based on the row
         // sizes calculated in step 2, steps 1 and 2 are repeated with the new min-content
         // contribution (once only).
-        repeatTracksSizingIfNeeded(sizingData, availableSpaceForColumns, availableSpaceForRows);
+        repeatTracksSizingIfNeeded(sizingData, availableSpaceForColumns, contentLogicalHeight());
 
         // Grid container should have the minimum height of a line if it's editable. That doesn't affect track sizing though.
         if (hasLineIfEmpty())
             setLogicalHeight(std::max(logicalHeight(), minimumLogicalHeightForEmptyLine()));
 
         applyStretchAlignmentToTracksIfNeeded(ForColumns, sizingData);
         applyStretchAlignmentToTracksIfNeeded(ForRows, sizingData);
 
         layoutGridItems(sizingData);
 
@@ skipping 109 matching lines @@
     minLogicalWidth += totalGuttersSize;
     maxLogicalWidth += totalGuttersSize;
 
     LayoutUnit scrollbarWidth = LayoutUnit(scrollbarLogicalWidth());
     minLogicalWidth += scrollbarWidth;
     maxLogicalWidth += scrollbarWidth;
 }
 
 void LayoutGrid::computeIntrinsicLogicalHeight(GridSizingData& sizingData)
 {
+    DCHECK(sizingData.isValidTransition(ForRows));
     ASSERT(tracksAreWiderThanMinTrackBreadth(ForColumns, sizingData));
     sizingData.setAvailableSpace(LayoutUnit());
     sizingData.freeSpace(ForRows) = LayoutUnit();
     sizingData.sizingOperation = IntrinsicSizeComputation;
     computeUsedBreadthOfGridTracks(ForRows, sizingData, m_minContentHeight, m_maxContentHeight);
 
     LayoutUnit totalGuttersSize = guttersSize(ForRows, 0, gridRowCount(), sizingData.sizingOperation);
     m_minContentHeight += totalGuttersSize;
     m_maxContentHeight += totalGuttersSize;
 
     ASSERT(tracksAreWiderThanMinTrackBreadth(ForRows, sizingData));
+    sizingData.nextState();

[jfernandez, 2016/09/14 21:54:46]

It's a bit confusing/peculiar that intrinsic size computation became part of the
regular track sizing algorithm. 

 }
 
 LayoutUnit LayoutGrid::computeIntrinsicLogicalContentHeightUsing(const Length& logicalHeightLength, LayoutUnit intrinsicContentHeight, LayoutUnit borderAndPadding) const
 {
     if (logicalHeightLength.isMinContent())
         return m_minContentHeight;
 
     if (logicalHeightLength.isMaxContent())
         return m_maxContentHeight;
 
@@ skipping 1241 matching lines @@
     for (const auto& trackIndex : autoSizedTracksIndex) {
         GridTrack* track = tracks.data() + trackIndex;
         LayoutUnit baseSize = track->baseSize() + sizeToIncrease;
         track->setBaseSize(baseSize);
     }
     availableSpace = LayoutUnit();
 }
 
 void LayoutGrid::layoutGridItems(GridSizingData& sizingData)
 {
+    sizingData.sizingOperation = TrackSizing;

[jfernandez, 2016/09/14 21:54:46]

Why we need to do this ?  Wouldn't be better place in the layoutBlock function ?
Or perhaps after finishing the computeIntrinsicLogicalHeight logic. 

[svillar, 2016/09/15 10:04:34]

We need this because the layout of the items involves calling some functions
whose behavior depend on that.

We didn't need that before because we always had a call to
computeUsedBreadthOfGridTracks(), something that does not happen now.

We can do it indeed inside computeIntrinsicLogicalHeight() as well. BTW I think
I'm renaming that function because it is a bit confusing. Perhaps
computeRowSizesForIndefiniteHeight() or something more explicit.

     populateGridPositionsForDirection(sizingData, ForColumns);
     populateGridPositionsForDirection(sizingData, ForRows);
     m_gridItemsOverflowingGridArea.resize(0);
 
     for (LayoutBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
         if (child->isOutOfFlowPositioned()) {
             prepareChildForPositionedLayout(*child);
             continue;
         }
 
@@ skipping 762 matching lines @@
     return isOrthogonalChild(child) ? childLocation.transposedPoint() : childLocation;
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset) const
 {
     if (!m_gridItemArea.isEmpty())
         GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink