is chrono considerd trusted time?

Hi, I am trying to understand if the porting to SGX of the [chrono](https://github.com/baidu/rust-sgx-sdk/tree/master/third_party/chrono) crate is considered safe or it's based on ocalls and anyone can modify the time?

Thanks

Start by reviewing the linked third_party/chrono port and its time-related implementation, then trace whether time retrieval uses OCALLs. Compare that behavior with SGX's trusted and untrusted boundaries; done means documenting whether chrono time can be modified by an untrusted host and the security implications.

Written by the indexing model from the issue text.