Do-not-commit: Count layout tree memory usage

third_party/WebKit/Source/core/paint/PaintLayer.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayer.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.cpp b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
index aabe1c5f5f715dabeeb6687319411f2a189aab07..bd6d311d459f8042bf7f8f0c37613f2609c402bd 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -211,6 +211,28 @@ LayoutRect PaintLayer::visualRect() const {
   return m_layoutObject.visualRect();
 }
 
+char PaintLayer::approximateHeapMemoryUsage() const {
+  int memory = 0;
+  if (m_ancestorDependentCompositingInputs)
+    memory += sizeof(AncestorDependentCompositingInputs);
+  if (m_scrollableArea) {
+    // TODO(pdr): Include the additional heap allocations in
+    // PaintLayerScrollableArea.
+    memory += sizeof(PaintLayerScrollableArea);
+  }
+  if (m_ancestorDependentCompositingInputs)
+    memory += sizeof(AncestorDependentCompositingInputs);
+  if (m_clipRectsCache)
+    memory += sizeof(ClipRectsCache);
+  if (m_stackingNode)
+    memory += sizeof(PaintLayerStackingNode);
+  if (m_previousPaintingClipRects)
+    memory += sizeof(ClipRects);
+  if (m_rareData)
+    memory += sizeof(PaintLayerRareData);
+  return memory;
+}
+
 PaintLayerCompositor* PaintLayer::compositor() const {
   if (!layoutObject().view())
     return 0;