[ Do not submit ] Prototype for invalidation analysis

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index 615432111823054f598e7f2684635d703c08b0fd..c12f38e97e4aaa2b976c50a4c2a9f17f41fc1c7e 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -32,6 +32,7 @@
 #include "core/editing/TextAffinity.h"
 #include "core/fetch/ImageResourceClient.h"
 #include "core/html/HTMLElement.h"
+#include "core/inspector/InspectorTraceEvents.h"
 #include "core/rendering/HitTestRequest.h"
 #include "core/rendering/PaintInvalidationState.h"
 #include "core/rendering/PaintPhase.h"
@@ -1419,6 +1420,11 @@ inline void RenderObject::setNeedsLayout(MarkingBehavior markParents, SubtreeLay
     bool alreadyNeededLayout = m_bitfields.selfNeedsLayout();
     setSelfNeedsLayout(true);
     if (!alreadyNeededLayout) {
+        TRACE_EVENT_INSTANT1(
+            TRACE_DISABLED_BY_DEFAULT("devtools.timeline.layoutInvalidationTracking"),
+            "LayoutInvalidationTracking",
+            "data",
+            InspectorLayoutInvalidationTrackingEvent::data(this));
         if (markParents == MarkContainingBlockChain && (!layouter || layouter->root() != this))
             markContainingBlocksForLayout(true, 0, layouter);
     }