[Sync] Remove unneeded 'using syncer::' lines and 'syncer::' scopings

sync/protocol/sync_protocol_error.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_PROTOCOL_SYNC_PROTOCOL_ERROR_H_
 #define SYNC_PROTOCOL_SYNC_PROTOCOL_ERROR_H_
 
 #include <string>
 
 #include "base/values.h"
 #include "sync/internal_api/public/base/model_type.h"
@@ skipping 49 matching lines @@
 
   // The default. No action.
   UNKNOWN_ACTION
 };
 
 struct SyncProtocolError {
   SyncProtocolErrorType error_type;
   std::string error_description;
   std::string url;
   ClientAction action;
-  syncer::ModelTypeSet error_data_types;
+  ModelTypeSet error_data_types;
   SyncProtocolError();
   ~SyncProtocolError();
   DictionaryValue* ToValue() const;
 };
 
 const char* GetSyncErrorTypeString(SyncProtocolErrorType type);
 const char* GetClientActionString(ClientAction action);
 }  // namespace syncer
 #endif  // SYNC_PROTOCOL_SYNC_PROTOCOL_ERROR_H_