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

sync/syncable/directory_backing_store.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_SYNCABLE_DIRECTORY_BACKING_STORE_H_
 #define SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 94 matching lines @@
   // Close save_dbhandle_.  Broken out for testing.
   void EndSave();
 
   // Removes each entry whose metahandle is in |handles| from the database.
   // Does synchronous I/O.  Returns false on error.
   bool DeleteEntries(const MetahandleSet& handles);
 
   // Drop all tables in preparation for reinitialization.
   void DropAllTables();
 
-  // Serialization helpers for syncer::ModelType.  These convert between
+  // Serialization helpers for ModelType.  These convert between
   // the ModelType enum and the values we persist in the database to identify
   // a model.  We persist a default instance of the specifics protobuf as the
   // ID, rather than the enum value.
   static ModelType ModelIdToModelTypeEnum(const void* data, int length);
   static std::string ModelTypeEnumToModelId(ModelType model_type);
 
   static std::string GenerateCacheGUID();
 
   // Runs an integrity check on the current database.  If the
   // integrity check fails, false is returned and error is populated
@@ skipping 33 matching lines @@
   // discarded.
   bool needs_column_refresh_;
 
   DISALLOW_COPY_AND_ASSIGN(DirectoryBackingStore);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_