Remove now unnecessary const_casts.

net/cert/ct_log_verifier_openssl.cc

Index: net/cert/ct_log_verifier_openssl.cc
diff --git a/net/cert/ct_log_verifier_openssl.cc b/net/cert/ct_log_verifier_openssl.cc
index b85c0d603d7a35f2bd6bf009562808d832cf7452..884ae8a4a402774832b02d0ee41523544af9b9a1 100644
--- a/net/cert/ct_log_verifier_openssl.cc
+++ b/net/cert/ct_log_verifier_openssl.cc
@@ -112,7 +112,7 @@ bool CTLogVerifier::VerifySignature(const base::StringPiece& data_to_sign,
           &ctx, data_to_sign.data(), data_to_sign.size()) &&
       1 == EVP_DigestVerifyFinal(
           &ctx,
-          reinterpret_cast<unsigned char*>(const_cast<char*>(signature.data())),
+          reinterpret_cast<const uint8_t*>(signature.data()),
           signature.size()));
 
   EVP_MD_CTX_cleanup(&ctx);