Remove #pragma once from crypto

crypto/keychain_mac.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_KEYCHAIN_MAC_H_
 #define CRYPTO_KEYCHAIN_MAC_H_
-#pragma once
 
 #include <Security/Security.h>
 
 #include "base/basictypes.h"
 #include "crypto/crypto_export.h"
 
 namespace crypto {
 
 // Wraps the KeychainServices API in a very thin layer, to allow it to be
 // mocked out for testing.
@@ skipping 74 matching lines @@
   // Calls CFRelease on the given ref, after checking that |ref| is non-NULL.
   virtual void Free(CFTypeRef ref) const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MacKeychain);
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_KEYCHAIN_MAC_H_