[Sync] Move //components/sync to the syncer namespace, take 2.

components/sync/driver/change_processor_mock.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 "components/sync/driver/change_processor_mock.h"
 
 #include "base/compiler_specific.h"
 
-namespace sync_driver {
+namespace syncer {
 
 ChangeProcessorMock::ChangeProcessorMock() : ChangeProcessor(nullptr) {}
 
 ChangeProcessorMock::~ChangeProcessorMock() {}
 
-}  // namespace sync_driver
+}  // namespace syncer