Oilpan: fix build after r198872.

Source/core/inspector/InspectorResourceContentLoader.cpp

Index: Source/core/inspector/InspectorResourceContentLoader.cpp
diff --git a/Source/core/inspector/InspectorResourceContentLoader.cpp b/Source/core/inspector/InspectorResourceContentLoader.cpp
index 3e0dbc877e04b03d6654429bfe02b463598ce09d..75b3563b1d60b1cb1868a5eabf876c3a31c7b943 100644
--- a/Source/core/inspector/InspectorResourceContentLoader.cpp
+++ b/Source/core/inspector/InspectorResourceContentLoader.cpp
@@ -159,7 +159,6 @@ InspectorResourceContentLoader::~InspectorResourceContentLoader()
 
 DEFINE_TRACE(InspectorResourceContentLoader)
 {
-    visitor->trace(m_callbacks);
     visitor->trace(m_inspectedFrame);
 }
 
@@ -196,7 +195,7 @@ void InspectorResourceContentLoader::checkDone()
 {
     if (!hasFinished())
         return;
-    WillBeHeapVector<OwnPtrWillBeMember<Closure>> callbacks;
+    Vector<OwnPtr<Closure>> callbacks;
     callbacks.swap(m_callbacks);
     for (const auto& callback : callbacks)
         (*callback)();