[Sync] Rename csync namespace to syncer

sync/engine/syncer_command.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 "sync/engine/syncer_command.h"
 
-namespace csync {
+namespace syncer {
 
 SyncerCommand::SyncerCommand() {}
 SyncerCommand::~SyncerCommand() {}
 
 SyncerError SyncerCommand::Execute(sessions::SyncSession* session) {
   SyncerError result = ExecuteImpl(session);
   return result;
 }
 
-}  // namespace csync
+}  // namespace syncer