Fix "unused variable" warnings.

chromeos/binder/transaction_data_reader.h

 // Copyright 2015 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 CHROMEOS_BINDER_TRANSACTION_DATA_READER_H_
 #define CHROMEOS_BINDER_TRANSACTION_DATA_READER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 55 matching lines @@
   // |command_broker| will be used for object ref-count operations.
   scoped_refptr<Object> ReadObject(CommandBroker* command_broker);
 
   // Reads a file descriptor.
   // The file descriptor is owned by the TransactionData, and it will be closed
   // when the TransactionData gets destroyed. You should duplicate the FD (e.g.
   // by calling dup()) to keep owning it.
   bool ReadFileDescriptor(int* fd);
 
  private:
-  const TransactionData& data_;
   BufferReader reader_;
 
   DISALLOW_COPY_AND_ASSIGN(TransactionDataReader);
 };
 
 }  // namespace binder
 
 #endif  // CHROMEOS_BINDER_TRANSACTION_DATA_READER_H_