Oilpan: trace non-owned InspectorOverlay references.

Source/core/inspector/InspectorProfilerAgent.cpp

Index: Source/core/inspector/InspectorProfilerAgent.cpp
diff --git a/Source/core/inspector/InspectorProfilerAgent.cpp b/Source/core/inspector/InspectorProfilerAgent.cpp
index c92e913c2f6439e5ab938f3d15fbeb72481bd366..a1a115bd1a5f5dae444d01a476367d3231374f3f 100644
--- a/Source/core/inspector/InspectorProfilerAgent.cpp
+++ b/Source/core/inspector/InspectorProfilerAgent.cpp
@@ -297,8 +297,8 @@ void InspectorProfilerAgent::didLeaveNestedRunLoop()
 DEFINE_TRACE(InspectorProfilerAgent)
 {
     visitor->trace(m_injectedScriptManager);
+    visitor->trace(m_overlay);
     InspectorBaseAgent::trace(visitor);
 }
 
 } // namespace blink
-