Add support for crypto::ECPrivateKey::Copy when built with BoringSSL

crypto/ec_private_key_openssl.cc

Index: crypto/ec_private_key_openssl.cc
diff --git a/crypto/ec_private_key_openssl.cc b/crypto/ec_private_key_openssl.cc
index b6b004cfb609b4204bed4eaab0d72b68389559e7..45657a73911cdd4ff37fe192fe8251a31bdd368e 100644
--- a/crypto/ec_private_key_openssl.cc
+++ b/crypto/ec_private_key_openssl.cc
@@ -85,6 +85,13 @@ ECPrivateKey::~ECPrivateKey() {
     EVP_PKEY_free(key_);
 }
 
+ECPrivateKey* ECPrivateKey::Copy() const {
+  scoped_ptr<ECPrivateKey> copy(new ECPrivateKey);
+  if (key_)
+    copy->key_ = EVP_PKEY_dup(key_);
+  return copy.release();
+}
+
 // static
 bool ECPrivateKey::IsSupported() { return true; }