Add DidSaveScrollOrScaleState flag to prevent restoreScrollPositionAndViewState restore from default

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

 /*
  * Copyright (C) 2005, 2006, 2008, 2011 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 25 matching lines @@
 namespace blink {
 
 static long long generateSequenceNumber() {
   // Initialize to the current time to reduce the likelihood of generating
   // identifiers that overlap with those from past/future browser sessions.
   static long long next = static_cast<long long>(currentTime() * 1000000.0);
   return ++next;
 }
 
 HistoryItem::HistoryItem()
-    : m_pageScaleFactor(0),
+    : m_didSaveScrollOrScaleState(false),
+      m_pageScaleFactor(0),
       m_itemSequenceNumber(generateSequenceNumber()),
       m_documentSequenceNumber(generateSequenceNumber()),
       m_scrollRestorationType(ScrollRestorationAuto) {}
 
 HistoryItem::~HistoryItem() {}
 
 const String& HistoryItem::urlString() const {
   return m_urlString;
 }
 
@@ skipping 27 matching lines @@
 void HistoryItem::setTarget(const String& target) {
   m_target = target;
 }
 
 const ScrollOffset& HistoryItem::visualViewportScrollOffset() const {
   return m_visualViewportScrollOffset;
 }
 
 void HistoryItem::setVisualViewportScrollOffset(const ScrollOffset& offset) {
   m_visualViewportScrollOffset = offset;
+  setDidSaveScrollOrScaleState(true);
 }
 
 const ScrollOffset& HistoryItem::getScrollOffset() const {
   return m_scrollOffset;
 }
 
 void HistoryItem::setScrollOffset(const ScrollOffset& offset) {
   m_scrollOffset = offset;
+  setDidSaveScrollOrScaleState(true);
 }
 
 float HistoryItem::pageScaleFactor() const {
   return m_pageScaleFactor;
 }
 
 void HistoryItem::setPageScaleFactor(float scaleFactor) {
   m_pageScaleFactor = scaleFactor;
+  setDidSaveScrollOrScaleState(true);
 }
 
 void HistoryItem::setDocumentState(const Vector<String>& state) {
   DCHECK(!m_documentState);
   m_documentStateVector = state;
 }
 
 void HistoryItem::setDocumentState(DocumentState* state) {
   m_documentState = state;
 }
@@ skipping 50 matching lines @@
   // FIXME: We should find a better way to check if this is the current
   // document.
   return equalIgnoringFragmentIdentifier(url(), doc->url());
 }
 
 DEFINE_TRACE(HistoryItem) {
   visitor->trace(m_documentState);
 }
 
 }  // namespace blink