Oilpan: add missing tracing of InspectorTracingAgent objects.

Source/core/inspector/InspectorTracingAgent.cpp

Index: Source/core/inspector/InspectorTracingAgent.cpp
diff --git a/Source/core/inspector/InspectorTracingAgent.cpp b/Source/core/inspector/InspectorTracingAgent.cpp
index 384a2181addeb05cc70d82039e7f274792a64ea2..b6ae30ebe2e24764429e7d6bef5651adecf2dbf7 100644
--- a/Source/core/inspector/InspectorTracingAgent.cpp
+++ b/Source/core/inspector/InspectorTracingAgent.cpp
@@ -13,6 +13,7 @@
 #include "core/inspector/InspectorState.h"
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/inspector/InspectorWorkerAgent.h"
+#include "core/page/Page.h"
 #include "platform/TraceEvent.h"
 
 namespace blink {
@@ -35,6 +36,13 @@ InspectorTracingAgent::InspectorTracingAgent(InspectorClient* client, InspectorW
 {
 }
 
+void InspectorTracingAgent::trace(Visitor* visitor)
+{
+    visitor->trace(m_workerAgent);
+    visitor->trace(m_page);
+    InspectorBaseAgent<InspectorTracingAgent>::trace(visitor);
+}
+
 void InspectorTracingAgent::restore()
 {
     emitMetadataEvents();