[Sync] Stop setting SyncEntity.insert_after_item_id in client

components/sync/engine_impl/commit_util.cc

 // Copyright 2013 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 "components/sync/engine_impl/commit_util.h"
 
 #include <limits>
 #include <string>
 #include <vector>
 
@@ skipping 148 matching lines @@
   sync_entry->set_ctime(TimeToProtoTime(meta_entry.GetCtime()));
   sync_entry->set_mtime(TimeToProtoTime(meta_entry.GetMtime()));
 
   SetAttachmentIds(meta_entry, sync_entry);
 
   // Handle bookmarks separately.
   if (meta_entry.GetSpecifics().has_bookmark()) {
     if (meta_entry.GetIsDel()) {
       sync_entry->set_deleted(true);
     } else {
-      // Both insert_after_item_id and position_in_parent fields are set only
-      // for legacy reasons.  See comments in sync.proto for more information.
-      const Id& prev_id = meta_entry.GetPredecessorId();
-      string prev_id_string =
-          prev_id.IsNull() ? string() : prev_id.GetServerId();
-      sync_entry->set_insert_after_item_id(prev_id_string);
+      // position_in_parent field is set only for legacy reasons.  See comments
+      // in sync.proto for more information.
       sync_entry->set_position_in_parent(
           meta_entry.GetUniquePosition().ToInt64());
       meta_entry.GetUniquePosition().ToProto(
           sync_entry->mutable_unique_position());
     }
     // Always send specifics for bookmarks.
     SetEntrySpecifics(meta_entry, sync_entry);
     return;
   }
 
@@ skipping 256 matching lines @@
 
   ProcessSuccessfulCommitResponse(commit_request_entry, server_entry,
                                   local_entry.GetId(), &local_entry,
                                   dirty_sync_was_set, deleted_folders);
   return response;
 }
 
 }  // namespace commit_util
 
 }  // namespace syncer