Oilpan: fix build after r183657.

Source/core/rendering/RenderGrid.cpp

Index: Source/core/rendering/RenderGrid.cpp
diff --git a/Source/core/rendering/RenderGrid.cpp b/Source/core/rendering/RenderGrid.cpp
index f23c028d3a6118a0a1ab80960942addb5ba41298..a459c51506629a0765ae64109fd4ab4de0e1b92e 100644
--- a/Source/core/rendering/RenderGrid.cpp
+++ b/Source/core/rendering/RenderGrid.cpp
@@ -33,6 +33,7 @@
 #include "core/rendering/style/GridCoordinate.h"
 #include "core/rendering/style/RenderStyle.h"
 #include "platform/LengthFunctions.h"
+#include "wtf/VectorTraits.h"
 
 namespace blink {
 
@@ -172,6 +173,7 @@ private:
 
 struct RenderGrid::GridSizingData {
     WTF_MAKE_NONCOPYABLE(GridSizingData);
+    STACK_ALLOCATED();
 public:
     GridSizingData(size_t gridColumnCount, size_t gridRowCount)
         : columnTracks(gridColumnCount)
@@ -186,7 +188,7 @@ public:
     // Performance optimization: hold onto these Vectors until the end of Layout to avoid repeated malloc / free.
     Vector<LayoutUnit> distributeTrackVector;
     Vector<GridTrack*> filteredTracks;
-    Vector<GridItemWithSpan> itemsSortedByIncreasingSpan;
+    WillBeHeapVector<GridItemWithSpan> itemsSortedByIncreasingSpan;
 };
 
 RenderGrid::RenderGrid(Element* element)
@@ -668,6 +670,7 @@ LayoutUnit RenderGrid::maxContentForChild(RenderBox& child, GridTrackSizingDirec
 // std::pair<RenderBox*, size_t> does not work either because we still need the GridCoordinate so we'd have to add an
 // extra hash lookup for each item at the beginning of RenderGrid::resolveContentBasedTrackSizingFunctionsForItems().
 class GridItemWithSpan {
+    ALLOW_ONLY_INLINE_ALLOCATION();
 public:
     GridItemWithSpan(RenderBox& gridItem, const GridCoordinate& coordinate, GridTrackSizingDirection direction)
         : m_gridItem(gridItem)
@@ -682,12 +685,33 @@ public:
 
     bool operator<(const GridItemWithSpan other) const { return m_span < other.m_span; }
 
+    void trace(Visitor* visitor)
+    {
+        visitor->trace(m_gridItem);
+    }
+
 private:
     RawPtrWillBeMember<RenderBox> m_gridItem;
     GridCoordinate m_coordinate;
     size_t m_span;
 };
 
+} // namespace blink
+
+namespace WTF  {
+
+template<>
+struct VectorTraits<blink::GridItemWithSpan> : SimpleClassVectorTraits<blink::GridItemWithSpan> {
+    // needsDestruction is by default defined in terms of IsPod<>, but as
+    // it doesn't handle embedded structs/enums (e.g., GridCoordinate),
+    // override it here.
+    static const bool needsDestruction = false;
+};

[haraken, 2014/10/14 11:41:30]

Can't we use WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS instead?

[sof, 2014/10/14 11:47:21]

Same as for GradientStop, the reason why not is that we have to override/fix
needsDestruction for this type.

I think we should consider introducing a macro for that, though. Can do that in
a followup, if so.

+
+} // namespace WTF
+
+namespace blink {
+
 void RenderGrid::resolveContentBasedTrackSizingFunctions(GridTrackSizingDirection direction, GridSizingData& sizingData, LayoutUnit& availableLogicalSpace)
 {
     sizingData.itemsSortedByIncreasingSpan.shrink(0);