Oilpan: fix build after r200730.

Source/core/loader/DocumentLoadTiming.cpp

 /*
  * Copyright (C) 2011 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 34 matching lines @@
     , m_fetchStart(0.0)
     , m_responseEnd(0.0)
     , m_loadEventStart(0.0)
     , m_loadEventEnd(0.0)
     , m_hasCrossOriginRedirect(false)
     , m_hasSameOriginAsPreviousDocument(false)
     , m_documentLoader(documentLoader)
 {
 }
 
+DEFINE_TRACE(DocumentLoadTiming)
+{
+    visitor->trace(m_documentLoader);
+}
+
 void DocumentLoadTiming::notifyDocumentTimingChanged()
 {
     if (m_documentLoader)
         m_documentLoader->didChangePerformanceTiming();
 }
 
 double DocumentLoadTiming::monotonicTimeToZeroBasedDocumentTime(double monotonicTime) const
 {
     if (!monotonicTime)
         return 0.0;
@@ skipping 103 matching lines @@
 }
 
 void DocumentLoadTiming::markRedirectEnd()
 {
     TRACE_EVENT_MARK("blink.user_timing", "redirectEnd");
     m_redirectEnd = monotonicallyIncreasingTime();
     notifyDocumentTimingChanged();
 }
 
 } // namespace blink