[Sync] Put everything in sync/api into csync namespace

sync/api/sync_data.h

 // 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.
 
 #ifndef SYNC_API_SYNC_DATA_H_
 #define SYNC_API_SYNC_DATA_H_
 #pragma once
 
 #include <iosfwd>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "sync/internal_api/public/syncable/model_type.h"
 #include "sync/internal_api/public/util/immutable.h"
 
 namespace sync_pb {
 class EntitySpecifics;
 class SyncEntity;
 }  // namespace sync_pb
 
+namespace csync {
+
 typedef syncable::ModelType SyncDataType;
 
 // A light-weight container for immutable sync data. Pass-by-value and storage
 // in STL containers are supported and encouraged if helpful.
 class SyncData {
  public:
   // Creates an empty and invalid SyncData.
   SyncData();
    ~SyncData();
 
@@ skipping 79 matching lines @@
   // Equal to csync::kInvalidId iff this is local.
   int64 id_;
 
   // The actual shared sync entity being held.
   ImmutableSyncEntity immutable_entity_;
 };
 
 // gmock printer helper.
 void PrintTo(const SyncData& sync_data, std::ostream* os);
 
+}  // namespace csync
+
 #endif  // SYNC_API_SYNC_DATA_H_