Google Style Guide "<chrono> is an unapproved C++11 header"

Question

Why is <chrono> an unapproved header in the Google CPP Guide? I can't find any direct mention of this in the Google CPP Style Guide. This point mentions portability issues with <ratio> and <cfenv> but nothing about <chrono>.

Answer 1

According to C++11 use in Chromium The reason is

Duplicated Time APIs in base/. Keep using the base/ classes.