Makes sync code persist the date the node was added. I'm hoping this covers

chrome/browser/bookmarks/bookmark_model.cc

 // Copyright (c) 2012 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 "chrome/browser/bookmarks/bookmark_model.h"
 
 #include <algorithm>
 #include <functional>
 
 #include "base/bind.h"
@@ skipping 450 matching lines @@
     const GURL& url,
     const Time& creation_time) {
   if (!loaded_ || !url.is_valid() || is_root_node(parent) ||
       !IsValidIndex(parent, index, true)) {
     NOTREACHED();
     return NULL;
   }
 
   bool was_bookmarked = IsBookmarked(url);
 
-  SetDateFolderModified(parent, creation_time);
+  // Syncing may result in dates older than the last modified date.
+  if (creation_time > parent->date_folder_modified())
+    SetDateFolderModified(parent, creation_time);
 
   BookmarkNode* new_node = new BookmarkNode(generate_next_node_id(), url);
   new_node->SetTitle(title);
   new_node->set_date_added(creation_time);
   new_node->set_type(BookmarkNode::URL);
 
   {
     // Only hold the lock for the duration of the insert.
     base::AutoLock url_lock(url_lock_);
     nodes_ordered_by_url_set_.insert(new_node);
@@ skipping 384 matching lines @@
 BookmarkLoadDetails* BookmarkModel::CreateLoadDetails() {
   BookmarkPermanentNode* bb_node =
       CreatePermanentNode(BookmarkNode::BOOKMARK_BAR);
   BookmarkPermanentNode* other_node =
       CreatePermanentNode(BookmarkNode::OTHER_NODE);
   BookmarkPermanentNode* mobile_node =
       CreatePermanentNode(BookmarkNode::MOBILE);
   return new BookmarkLoadDetails(bb_node, other_node, mobile_node,
                                  new BookmarkIndex(profile_), next_node_id_);
 }