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

components/sync/api/data_batch.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_SYNC_API_DATA_BATCH_H_
 #define COMPONENTS_SYNC_API_DATA_BATCH_H_
 
 #include <algorithm>
 #include <memory>
 #include <string>
 #include <utility>
 
 #include "components/sync/api/entity_data.h"
 
-namespace syncer_v2 {
+namespace syncer {
 
 typedef std::pair<std::string, std::unique_ptr<EntityData>> KeyAndData;
 
 // Interface used by the processor to read data requested from the service.
 class DataBatch {
  public:
   DataBatch() {}
   virtual ~DataBatch() {}
 
   // Returns if the data batch has another pair or not.
   virtual bool HasNext() const = 0;
 
   // Returns a pair of storage tag and owned entity data object. Invoking this
   // method will remove the pair from the batch, and should not be called if
   // HasNext() returns false.
   virtual KeyAndData Next() = 0;
 };
 
-}  // namespace syncer_v2
+}  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_API_DATA_BATCH_H_