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

sync/internal_api/public/read_node.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_INTERNAL_API_PUBLIC_READ_NODE_H_
 #define SYNC_INTERNAL_API_PUBLIC_READ_NODE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 11 matching lines @@
   // of Init to populate the ReadNode with a database entry.
   explicit ReadNode(const BaseTransaction* transaction);
   virtual ~ReadNode();
 
   // A client must use one (and only one) of the following Init variants to
   // populate the node.
 
   // BaseNode implementation.
   virtual InitByLookupResult InitByIdLookup(int64 id) OVERRIDE;
   virtual InitByLookupResult InitByClientTagLookup(
-      syncer::ModelType model_type,
+      ModelType model_type,
       const std::string& tag) OVERRIDE;
 
   // There is always a root node, so this can't fail.  The root node is
   // never mutable, so root lookup is only possible on a ReadNode.
   void InitByRootLookup();
 
   // Each server-created permanent node is tagged with a unique string.
   // Look up the node with the particular tag.  If it does not exist,
   // return false.
   InitByLookupResult InitByTagLookup(const std::string& tag);
@@ skipping 13 matching lines @@
 
   // The sync API transaction that is the parent of this node.
   const BaseTransaction* transaction_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadNode);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_READ_NODE_H_