crypto: Add critpto_api.h and annotate the current exports needed to run

crypto/secure_hash.h

 // Copyright (c) 2011 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_api.h"
 
 namespace crypto {
 
 // A wrapper to calculate secure hashes incrementally, allowing to
 // be used when the full input is not known in advance.
-class SecureHash {
+class CRYPTO_API SecureHash {
  public:
   enum Algorithm {
     SHA256,
   };
   virtual ~SecureHash() {}
 
   static SecureHash* Create(Algorithm type);
 
   virtual void Update(const void* input, size_t len) = 0;
   virtual void Finish(void* output, size_t len) = 0;
 
  protected:
   SecureHash() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SecureHash);
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_SECURE_HASH_H_