Currently the zlib used by Chromium has Intel specific optimizations applied on the top level folder.

This is undesirable as it violates the design used in zlib upstream where platform specific optimizations are hosted in a 'contrib' folder.

One of the active zlib forks (zlib-ng) follows a similar idea, but organizing CPU architecture specific code accordingly (i.e.: https://github.com/Dead2/zlib-ng/tree/develop/arch).

We introduced the 'contrib' folder structure in the first ARM specific optimization (https://chromium-review.googlesource.com/c/chromium/src/+/627098).

With the objective of trying to upstream this patches and making Chromium's zlib fork more manageable, the idea is to move the Intel specific code to a new folder tentatively called 'contrib/x86'.

Advantages:
a) That will allow the removal of the '.patch' files in the top directory
b) Chromium's zlib will become more similar with upstream (both canonical zlib and zlib-ng)
c) This will allow better odds of upstreaming this optimizations

Optimizations that are not architecture specific can be hosted in a neutral folder (e.g. contrib/chromium-portable).