Do-not-commit: Count layout tree memory usage

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

Index: third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
index 33672ccc2d653469824876d32a0794e44c97fdf4..db1ace938936f242fbc3771ea2a01afa597f6815 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
@@ -260,6 +260,17 @@ void LayoutBoxModelObject::willBeDestroyed() {
   destroyLayer();
 }
 
+char LayoutBoxModelObject::approximateHeapMemoryUsage() const {
+  int memory = LayoutObject::approximateHeapMemoryUsage();
+  if (m_layer) {
+    memory += sizeof(PaintLayer);
+    memory += m_layer->approximateHeapMemoryUsage();
+  }
+  if (m_rareData)
+    memory += sizeof(LayoutBoxModelObjectRareData);
+  return memory;
+}
+
 void LayoutBoxModelObject::styleWillChange(StyleDifference diff,
                                            const ComputedStyle& newStyle) {
   // This object's layer may begin or cease to be a stacking context, in which