Changing scroll and view state in onpopstate shouldn't overwrite back/forward state restore

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 24 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()
-    : did_save_scroll_or_scale_state_(false),
-      page_scale_factor_(0),
-      item_sequence_number_(GenerateSequenceNumber()),
+    : item_sequence_number_(GenerateSequenceNumber()),
       document_sequence_number_(GenerateSequenceNumber()),
       scroll_restoration_type_(kScrollRestorationAuto) {}
 
 HistoryItem::~HistoryItem() {}
 
 const String& HistoryItem::UrlString() const {
   return url_string_;
 }
 
 KURL HistoryItem::Url() const {
@@ skipping 12 matching lines @@
 void HistoryItem::SetURL(const KURL& url) {
   SetURLString(url.GetString());
 }
 
 void HistoryItem::SetReferrer(const Referrer& referrer) {
   // This should be a CHECK.
   referrer_ = SecurityPolicy::GenerateReferrer(referrer.referrer_policy, Url(),
                                                referrer.referrer);
 }
 
-const ScrollOffset& HistoryItem::VisualViewportScrollOffset() const {
-  return visual_viewport_scroll_offset_;
-}
-
 void HistoryItem::SetVisualViewportScrollOffset(const ScrollOffset& offset) {
-  visual_viewport_scroll_offset_ = offset;
-  SetDidSaveScrollOrScaleState(true);
-}
-
-const ScrollOffset& HistoryItem::GetScrollOffset() const {
-  return scroll_offset_;
+  if (!view_state_)
+    view_state_ = WTF::MakeUnique<ViewState>();
+  view_state_->visual_viewport_scroll_offset_ = offset;
 }
 
 void HistoryItem::SetScrollOffset(const ScrollOffset& offset) {
-  scroll_offset_ = offset;
-  SetDidSaveScrollOrScaleState(true);
-}
-
-float HistoryItem::PageScaleFactor() const {
-  return page_scale_factor_;
+  if (!view_state_)
+    view_state_ = WTF::MakeUnique<ViewState>();
+  view_state_->scroll_offset_ = offset;
 }
 
 void HistoryItem::SetPageScaleFactor(float scale_factor) {
-  page_scale_factor_ = scale_factor;
-  SetDidSaveScrollOrScaleState(true);
+  if (!view_state_)
+    view_state_ = WTF::MakeUnique<ViewState>();
+  view_state_->page_scale_factor_ = scale_factor;
 }
 
 void HistoryItem::SetDocumentState(const Vector<String>& state) {
   DCHECK(!document_state_);
   document_state_vector_ = state;
 }
 
 void HistoryItem::SetDocumentState(DocumentState* state) {
   document_state_ = state;
 }
@@ skipping 58 matching lines @@
     request.AddHTTPOriginIfNeeded(referrer_.referrer);
   }
   return request;
 }
 
 DEFINE_TRACE(HistoryItem) {
   visitor->Trace(document_state_);
 }
 
 }  // namespace blink