sync: Start moving away from PREV_ID and NEXT_ID

sync/engine/build_commit_command.cc

 // Copyright 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 "sync/engine/build_commit_command.h"
 
 #include <limits>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 179 matching lines @@
     }
     sync_entry->set_ctime(TimeToProtoTime(meta_entry.Get(syncable::CTIME)));
     sync_entry->set_mtime(TimeToProtoTime(meta_entry.Get(syncable::MTIME)));
 
     // Deletion is final on the server, let's move things and then delete them.
     if (meta_entry.Get(IS_DEL)) {
       sync_entry->set_deleted(true);
     } else {
       if (meta_entry.Get(SPECIFICS).has_bookmark()) {
         // Common data in both new and old protocol.
-        const Id& prev_id = meta_entry.Get(syncable::PREV_ID);
+        const Id& prev_id = meta_entry.GetPredecessorId();
         string prev_id_string =
             prev_id.IsRoot() ? string() : prev_id.GetServerId();
         sync_entry->set_insert_after_item_id(prev_id_string);
 
         // Compute a numeric position based on what we know locally.
         std::pair<int64, int64> position_block(
             GetFirstPosition(), GetLastPosition());
         std::map<Id, std::pair<int64, int64> >::iterator prev_pos =
             position_map.find(prev_id);
         if (prev_pos != position_map.end()) {
@@ skipping 49 matching lines @@
   if (delta <= static_cast<uint64>(GetGap()*2))
     return lo + (static_cast<int64>(delta) + 7) / 8;  // Interpolate.
   else if (lo == GetFirstPosition())
     return hi - GetGap();  // Extend range just before successor.
   else
     return lo + GetGap();  // Use or extend range just after predecessor.
 }
 
 
 }  // namespace syncer