Oilpan: extend tracing over WebFrame trees.

Source/web/OpenedFrameTracker.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "web/OpenedFrameTracker.h"
 
+#include "platform/heap/Handle.h"
 #include "public/web/WebFrame.h"
 
 namespace blink {
 
 OpenedFrameTracker::OpenedFrameTracker()
 {
 }
 
 OpenedFrameTracker::~OpenedFrameTracker()
 {
+#if !ENABLE(OILPAN)
+    // Oilpan takes care of clearing weak m_opener fields during GC.
     updateOpener(0);
+#endif
 }
 
 bool OpenedFrameTracker::isEmpty() const
 {
     return m_openedFrames.isEmpty();
 }
 
 void OpenedFrameTracker::add(WebFrame* frame)
 {
     m_openedFrames.add(frame);
 }
 
 void OpenedFrameTracker::remove(WebFrame* frame)
 {
     m_openedFrames.remove(frame);
 }
 
 void OpenedFrameTracker::updateOpener(WebFrame* frame)
 {
     HashSet<WebFrame*>::iterator end = m_openedFrames.end();
     for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
         (*it)->m_opener = frame;
 }
 
+void OpenedFrameTracker::traceFrames(Visitor* visitor)
+{
+#if ENABLE(OILPAN)
+    HashSet<WebFrame*>::iterator end = m_openedFrames.end();
+    for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
+        WebFrame::traceFrame(visitor, *it);
+#endif
+}
+
 } // namespace blink