Revert 78354 - Revert 78236 - Merge r76205, crbug 54262...

WebCore/history/HistoryItem.h

 /*
  * Copyright (C) 2006, 2008 Apple 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 70 matching lines @@
     }
     static PassRefPtr<HistoryItem> create(const KURL& url, const String& target, const String& parent, const String& title)
     {
         return adoptRef(new HistoryItem(url, target, parent, title));
     }
     
     ~HistoryItem();
     
     PassRefPtr<HistoryItem> copy() const;
     
+    // Resets the HistoryItem to its initial state, as returned by create().
+    void reset();
+    
     const String& originalURLString() const;
     const String& urlString() const;
     const String& title() const;
     
     bool isInPageCache() const { return m_cachedPage; }
     
     double lastVisitedTime() const;
     
     void setAlternateTitle(const String& alternateTitle);
     const String& alternateTitle() const;
@@ skipping 33 matching lines @@
     void setIsTargetItem(bool);
     
     void setStateObject(PassRefPtr<SerializedScriptValue> object);
     SerializedScriptValue* stateObject() const { return m_stateObject.get(); }
 
     void setItemSequenceNumber(long long number) { m_itemSequenceNumber = number; }
     long long itemSequenceNumber() const { return m_itemSequenceNumber; }
 
     void setDocumentSequenceNumber(long long number) { m_documentSequenceNumber = number; }
     long long documentSequenceNumber() const { return m_documentSequenceNumber; }
-    
+
     void setFormInfoFromRequest(const ResourceRequest&);
     void setFormData(PassRefPtr<FormData>);
     void setFormContentType(const String&);
 
     void recordInitialVisit();
 
     void setVisitCount(int);
     void setLastVisitWasFailure(bool wasFailure) { m_lastVisitWasFailure = wasFailure; }
     void setLastVisitWasHTTPNonGet(bool wasNotGet) { m_lastVisitWasHTTPNonGet = wasNotGet; }
 
@@ skipping 89 matching lines @@
     HistoryItemVector m_children;
     
     bool m_lastVisitWasFailure;
     bool m_isTargetItem;
     int m_visitCount;
     Vector<int> m_dailyVisitCounts;
     Vector<int> m_weeklyVisitCounts;
 
     OwnPtr<Vector<String> > m_redirectURLs;
 
+    // If two HistoryItems have the same item sequence number, then they are
+    // clones of one another.  Traversing history from one such HistoryItem to
+    // another is a no-op.  HistoryItem clones are created for parent and
+    // sibling frames when only a subframe navigates.
     long long m_itemSequenceNumber;
 
+    // If two HistoryItems have the same document sequence number, then they
+    // refer to the same instance of a document.  Traversing history from one
+    // such HistoryItem to another preserves the document.
+    long long m_documentSequenceNumber;
+
     // Support for HTML5 History
     RefPtr<SerializedScriptValue> m_stateObject;
-    long long m_documentSequenceNumber;
     
     // info used to repost form data
     RefPtr<FormData> m_formData;
     String m_formContentType;
 
     // PageCache controls these fields.
     HistoryItem* m_next;
     HistoryItem* m_prev;
     RefPtr<CachedPage> m_cachedPage;
     
@@ skipping 13 matching lines @@
 }; //class HistoryItem
 
 } //namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 extern "C" int showTree(const WebCore::HistoryItem*);
 #endif
 
 #endif // HISTORYITEM_H