Add new constructor to HKDF that allows the client and server key/IV

crypto/hkdf.h

Index: crypto/hkdf.h
diff --git a/crypto/hkdf.h b/crypto/hkdf.h
index 6b7d00dd6e200bd093cb8311d211d8d0f5a05efd..b8c07c6c6694f57d009cf7ea93c9c5772b25184e 100644
--- a/crypto/hkdf.h
+++ b/crypto/hkdf.h
@@ -40,6 +40,17 @@ class CRYPTO_EXPORT HKDF {
        size_t key_bytes_to_generate,
        size_t iv_bytes_to_generate,
        size_t subkey_secret_bytes_to_generate);
+
+  // An alternative constructor that allows the client and server key/IV
+  // lengths to be different.
+  HKDF(const base::StringPiece& secret,
+       const base::StringPiece& salt,
+       const base::StringPiece& info,
+       size_t client_key_bytes_to_generate,
+       size_t server_key_bytes_to_generate,
+       size_t client_iv_bytes_to_generate,
+       size_t server_iv_bytes_to_generate,
+       size_t subkey_secret_bytes_to_generate);
   ~HKDF();
 
   base::StringPiece client_write_key() const {