This directory was created manually and not imported from Chromium. It was created to remove the divergence we had where we had to rename #include "third_party/zlib/zlib.h" line to #include <zlib.h>. This is due to the fact that we don‘t import Chromium’s zlib and we use zlib from AOSP. In order to workaround that, we redirect traffic from third_party/zlib/zlib.h to AOSP's zlib.