Remove openssl_bio_string.

crypto/openssl_bio_string.h

-// Copyright 2014 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 CRYPTO_OPENSSL_BIO_STRING_H_
-#define CRYPTO_OPENSSL_BIO_STRING_H_
-
-#include <string>
-
-#include "crypto/crypto_export.h"
-
-// From <openssl/bio.h>
-typedef struct bio_st BIO;
-
-namespace crypto {
-
-// Creates a new BIO that can be used with OpenSSL's various output functions,
-// and which will write all output directly into |out|. This is primarily
-// intended as a utility to reduce the amount of copying and separate
-// allocations when performing extensive string modifications or streaming
-// within OpenSSL.
-//
-// Note: |out| must remain valid for the duration of the BIO.
-CRYPTO_EXPORT BIO* BIO_new_string(std::string* out);
-
-}  // namespace crypto
-
-#endif  // CRYPTO_OPENSSL_BIO_STRING_H_
-