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

content/renderer/history_serialization.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/history_serialization.h"
 
 #include <stddef.h>
 
 #include "base/strings/nullable_string16.h"
 #include "content/child/web_url_request_util.h"
@@ skipping 81 matching lines @@
     item.SetStateObject(WebSerializedScriptValue::FromString(
         WebString::FromUTF16(state.state_object)));
   }
   WebVector<WebString> document_state(state.document_state.size());
   std::transform(state.document_state.begin(), state.document_state.end(),
                  document_state.begin(), [](const base::NullableString16& s) {
                    return WebString::FromUTF16(s);
                  });
   item.SetDocumentState(document_state);
   item.SetScrollRestorationType(state.scroll_restoration_type);
-  item.SetVisualViewportScrollOffset(state.visual_viewport_scroll_offset);
-  item.SetScrollOffset(state.scroll_offset);
-  item.SetPageScaleFactor(state.page_scale_factor);
-  item.SetDidSaveScrollOrScaleState(state.did_save_scroll_or_scale_state);
+
+  if (state.did_save_scroll_or_scale_state) {
+    item.SetVisualViewportScrollOffset(state.visual_viewport_scroll_offset);
+    item.SetScrollOffset(state.scroll_offset);
+    item.SetPageScaleFactor(state.page_scale_factor);
+  }
 
   // These values are generated at WebHistoryItem construction time, and we
   // only want to override those new values with old values if the old values
   // are defined.  A value of 0 means undefined in this context.
   if (state.item_sequence_number)
     item.SetItemSequenceNumber(state.item_sequence_number);
   if (state.document_sequence_number)
     item.SetDocumentSequenceNumber(state.document_sequence_number);
 
   item.SetHTTPContentType(
@@ skipping 37 matching lines @@
   if (!DecodePageState(page_state.ToEncodedData(), &state))
     return std::unique_ptr<HistoryEntry>();
 
   std::unique_ptr<HistoryEntry> entry(new HistoryEntry());
   RecursivelyGenerateHistoryItem(state.top, entry->root_history_node());
 
   return entry;
 }
 
 }  // namespace content