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

sync/api/sync_change_processor.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_CHANGE_PROCESSOR_H_
 #define SYNC_API_SYNC_CHANGE_PROCESSOR_H_
 #pragma once
 
 #include <vector>
 
 #include "sync/api/sync_error.h"
 
-class SyncChange;
-
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
+namespace csync {
+
+class SyncChange;
+
 typedef std::vector<SyncChange> SyncChangeList;
 
 // An interface for services that handle receiving SyncChanges.
 class SyncChangeProcessor {
  public:
   SyncChangeProcessor();
   virtual ~SyncChangeProcessor();
 
   // Process a list of SyncChanges.
   // Returns: A default SyncError (IsSet() == false) if no errors were
   //          encountered, and a filled SyncError (IsSet() == true)
   //          otherwise.
   // Inputs:
   //   |from_here|: allows tracking of where sync changes originate.
   //   |change_list|: is the list of sync changes in need of processing.
   virtual SyncError ProcessSyncChanges(
       const tracked_objects::Location& from_here,
       const SyncChangeList& change_list) = 0;
 };
 
+}  // namespace csync
+
 #endif  // SYNC_API_SYNC_CHANGE_PROCESSOR_H_