Don't reuse HistoryItems for multiple navigations

Source/core/loader/FrameLoader.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * 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:
  *
@@ skipping 153 matching lines @@
 
     bool shouldClose();
     void dispatchUnloadEvent();
 
     bool allowPlugins(ReasonForCallingAllowPlugins);
 
     void updateForSameDocumentNavigation(const KURL&, SameDocumentNavigationSource, PassRefPtr<SerializedScriptValue>, HistoryScrollRestorationType, FrameLoadType);
 
     HistoryItem* currentItem() const { return m_currentItem.get(); }
     void saveScrollState();
-    void clearScrollPositionAndViewState();
 
     void restoreScrollPositionAndViewState();
 
     DECLARE_TRACE();
 
 private:
     void checkTimerFired(Timer<FrameLoader>*);
     void didAccessInitialDocumentTimerFired(Timer<FrameLoader>*);
 
     bool prepareRequestForThisFrame(FrameLoadRequest&);
     static void setReferrerForFrameRequest(ResourceRequest&, ShouldSendReferrer, Document*);
     FrameLoadType determineFrameLoadType(const FrameLoadRequest&);
 
     SubstituteData defaultSubstituteDataForURL(const KURL&);
 
     bool shouldPerformFragmentNavigation(bool isFormSubmission, const String& httpMethod, FrameLoadType, const KURL&);
     void scrollToFragmentWithParentBoundary(const KURL&);
 
     void startLoad(FrameLoadRequest&, FrameLoadType, NavigationPolicy);
 
-
-    void setHistoryItemStateForCommit(HistoryCommitType, bool isPushOrReplaceState = false, HistoryScrollRestorationType = ScrollRestorationAuto, PassRefPtr<SerializedScriptValue> = nullptr);
+    enum class HistoryNavigationType {
+        DifferentDocument,
+        Fragment,
+        HistoryApi
+    };
+    void setHistoryItemStateForCommit(HistoryCommitType, HistoryNavigationType);
 
     void loadInSameDocument(const KURL&, PassRefPtr<SerializedScriptValue> stateObject, FrameLoadType, ClientRedirectPolicy);
 
     void scheduleCheckCompleted();
 
     RawPtrWillBeMember<LocalFrame> m_frame;
 
     // FIXME: These should be OwnPtr<T> to reduce build times and simplify
     // header dependencies unless performance testing proves otherwise.
     // Some of these could be lazily created for memory savings on devices.
@@ skipping 48 matching lines @@
     Timer<FrameLoader> m_didAccessInitialDocumentTimer;
 
     SandboxFlags m_forcedSandboxFlags;
 
     bool m_dispatchingDidClearWindowObjectInMainWorld;
 };
 
 } // namespace blink
 
 #endif // FrameLoader_h