Remove #pragma once from crypto

crypto/secure_hash.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 CRYPTO_SECURE_HASH_H_
 #define CRYPTO_SECURE_HASH_H_
-#pragma once
 
 #include "base/basictypes.h"
 #include "crypto/crypto_export.h"
 
 class Pickle;
 class PickleIterator;
 
 namespace crypto {
 
 // A wrapper to calculate secure hashes incrementally, allowing to
@@ skipping 24 matching lines @@
  protected:
   SecureHash() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SecureHash);
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_SECURE_HASH_H_