Fix non-noise cpplint errors in //crypto.

crypto/ec_private_key.cc

Index: crypto/ec_private_key.cc
diff --git a/crypto/ec_private_key.cc b/crypto/ec_private_key.cc
index 9914c5dde866e9f2e47b9a747ab7584cefff4d19..08fd75dec3c95f74bb381c082e8000dc7f02fa28 100644
--- a/crypto/ec_private_key.cc
+++ b/crypto/ec_private_key.cc
@@ -46,9 +46,9 @@ bool ExportKeyWithBio(const void* key,
   if (!export_fn(bio.get(), key))
     return false;
 
-  char* data = nullptr;
-  long len = BIO_get_mem_data(bio.get(), &data);
-  if (!data || len < 0)
+  const uint8_t* data;
+  size_t len;
+  if (!BIO_mem_contents(bio.get(), &data, &len))
     return false;
 
   output->assign(data, data + len);