[css-grid] Fix crash when using auto repeat for indefinite widths

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 6d8864e4a0d6d97a786ebe9bb66b5cfebf6bd4b9..9f7b39bbb16bedbaa3beb539db684fe447a6fa34 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -443,7 +443,7 @@ void LayoutGrid::layoutBlock(bool relayoutChildren)
 
         TextAutosizer::LayoutScope textAutosizerLayoutScope(this, &layoutScope);
 
-        placeItemsOnGrid();
+        placeItemsOnGrid(TrackSizing);
 
         GridSizingData sizingData(gridColumnCount(), gridRowCount());
 
@@ -511,7 +511,8 @@ LayoutUnit LayoutGrid::guttersSize(GridTrackSizingDirection direction, size_t sp
 
 void LayoutGrid::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 {
-    const_cast<LayoutGrid*>(this)->placeItemsOnGrid();
+    // TODO(svillar): check the comment in clearGridDataAndMarkAsDirty() to remove these two const_cast.
+    const_cast<LayoutGrid*>(this)->placeItemsOnGrid(IntrinsicSizeComputation);
 
     GridSizingData sizingData(gridColumnCount(), gridRowCount());
     sizingData.freeSpaceForDirection(ForColumns) = LayoutUnit();
@@ -525,6 +526,10 @@ void LayoutGrid::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, Layo
     LayoutUnit scrollbarWidth = LayoutUnit(scrollbarLogicalWidth());
     minLogicalWidth += scrollbarWidth;
     maxLogicalWidth += scrollbarWidth;
+
+    // Mark the grid as dirty as we need to recompute the auto repeat columns during layout.
+    if (m_autoRepeatColumns)
+        clearGridDataAndMarkAsDirty();

[Manuel Rego, 2016/07/11 09:47:42]

But we're already setting m_autoRepeatColumns|Rows on
placeItemsOnGrid().
Do we really need this clear()?

Also, could you explain in the description all the changes related to "mutable"
attributes and so on?

[svillar1, 2016/07/11 10:34:48]

If you don't mark the grid as empty here, placeItemsOnGrid() won't do anything
(as it has an early return). And you must recompute the tracks because the
number of auto repeat columns will be likely different.
 
OK I could mention that I clear all the mutable attributes in a specific method
if you want.

[Manuel Rego, 2016/07/11 11:10:56]

True, I missed that.

 }
 
 void LayoutGrid::computeIntrinsicLogicalHeight(GridSizingData& sizingData)
@@ -1384,14 +1389,17 @@ size_t LayoutGrid::computeAutoRepeatTracksCount(GridTrackSizingDirection directi
     return repetitions;
 }
 
-void LayoutGrid::placeItemsOnGrid()
+void LayoutGrid::placeItemsOnGrid(SizingOperation inlineAxisSizingOperation)
 {
     if (!m_gridIsDirty)
         return;
 
     ASSERT(m_gridItemArea.isEmpty());
 
-    m_autoRepeatColumns = computeAutoRepeatTracksCount(ForColumns);
+    if (inlineAxisSizingOperation == IntrinsicSizeComputation)
+        m_autoRepeatColumns = styleRef().gridAutoRepeatColumns().isEmpty() ? 0 : 1;
+    else
+        m_autoRepeatColumns = computeAutoRepeatTracksCount(ForColumns);
     m_autoRepeatRows = computeAutoRepeatTracksCount(ForRows);
 
     populateExplicitGridAndOrderIterator();
@@ -1615,6 +1623,21 @@ GridTrackSizingDirection LayoutGrid::autoPlacementMinorAxisDirection() const
     return style()->isGridAutoFlowDirectionColumn() ? ForRows : ForColumns;
 }
 
+void LayoutGrid::clearGridDataAndMarkAsDirty() const
+{
+    // TODO(svillar): The track sizing algorithm is used for preferredLogicalWidths
+    // computations. This means that some attributes of this class will be modified during that
+    // process. We should make the algorithm work against some interface that would allow us not to
+    // have to change these attributes while computing the intrinsic sizes.
+    m_grid.resize(0);
+    m_gridItemArea.clear();
+    m_gridItemsOverflowingGridArea.resize(0);
+    m_gridItemsIndexesMap.clear();
+    m_autoRepeatColumns = 0;
+    m_autoRepeatRows = 0;
+    m_gridIsDirty = true;
+}
+
 void LayoutGrid::dirtyGrid()
 {
     if (m_gridIsDirty)
@@ -1627,11 +1650,7 @@ void LayoutGrid::dirtyGrid()
     // the grid and its children are correctly laid out according to the new style rules.
     setNeedsLayout(LayoutInvalidationReason::GridChanged);
 
-    m_grid.resize(0);
-    m_gridItemArea.clear();
-    m_gridItemsOverflowingGridArea.resize(0);
-    m_gridItemsIndexesMap.clear();
-    m_gridIsDirty = true;
+    clearGridDataAndMarkAsDirty();
 }
 
 static const StyleContentAlignmentData& normalValueBehavior()