Split the frame tree logic out of HistoryItem

Source/web/WebHistoryItem.cpp

 /*
  * Copyright (C) 2009 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 219 matching lines @@
 {
     ensureMutable();
     m_private->setFormData(httpBody);
 }
 
 WebVector<WebHistoryItem> WebHistoryItem::children() const
 {
     return m_private->children();
 }
 
+void WebHistoryItem::setChildren(const WebVector<WebHistoryItem>& items)
+{
+    ensureMutable();
+    m_private->clearChildren();
+    for (size_t i = 0; i < items.size(); ++i)
+        m_private->addChildItem(items[i]);
+}
+
 void WebHistoryItem::appendToChildren(const WebHistoryItem& item)
 {
     ensureMutable();
     m_private->addChildItem(item);
 }
 
 WebVector<WebString> WebHistoryItem::getReferencedFilePaths() const
 {
     HashSet<String> filePaths;
     addReferencedFilePaths(m_private.get(), filePaths);
@@ skipping 19 matching lines @@
     return m_private.get();
 }
 
 void WebHistoryItem::ensureMutable()
 {
     if (!m_private->hasOneRef())
         m_private = m_private->copy();
 }
 
 } // namespace blink