Add DidSaveScrollOrScaleState flag to prevent restoreScrollPositionAndViewState restore from default

third_party/WebKit/Source/core/loader/HistoryItem.h

 /*
  * Copyright (C) 2006, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Research In Motion Limited. 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
@@ skipping 42 matching lines @@
 
   const String& urlString() const;
   KURL url() const;
 
   const Referrer& referrer() const;
   const String& target() const;
 
   EncodedFormData* formData();
   const AtomicString& formContentType() const;
 
+  void setDidSaveScrollOrScaleState(bool didSaveScrollOrScaleState) {
+    m_didSaveScrollOrScaleState = didSaveScrollOrScaleState;
+  }
+
+  bool didSaveScrollOrScaleState() const { return m_didSaveScrollOrScaleState; }
+
   const ScrollOffset& visualViewportScrollOffset() const;
   void setVisualViewportScrollOffset(const ScrollOffset&);
   const ScrollOffset& getScrollOffset() const;
   void setScrollOffset(const ScrollOffset&);
 
   float pageScaleFactor() const;
   void setPageScaleFactor(float);
 
   Vector<String> getReferencedFilePaths();
   const Vector<String>& getDocumentState();
@@ skipping 34 matching lines @@
 
   DECLARE_TRACE();
 
  private:
   HistoryItem();
 
   String m_urlString;
   Referrer m_referrer;
   String m_target;
 
+  bool m_didSaveScrollOrScaleState;
   ScrollOffset m_visualViewportScrollOffset;
   ScrollOffset m_scrollOffset;
   float m_pageScaleFactor;
   Vector<String> m_documentStateVector;
   Member<DocumentState> m_documentState;
 
   // 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.
   int64_t 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.
   int64_t m_documentSequenceNumber;
 
   // Type of the scroll restoration for the history item determines if scroll
   // position should be restored when it is loaded during history traversal.
   HistoryScrollRestorationType m_scrollRestorationType;
 
   // Support for HTML5 History
   RefPtr<SerializedScriptValue> m_stateObject;
 
   // info used to repost form data
   RefPtr<EncodedFormData> m_formData;
   AtomicString m_formContentType;
-
 };  // class HistoryItem
 
 }  // namespace blink
 
 #endif  // HISTORYITEM_H