UserAgent: Mozilla/5.0 (X11; NetBSD amd64; rv:51.0) Gecko/20100101 Firefox/51.0

Steps to reproduce the problem:
Try to build on a *BSD (freebsd, openbsd, netbsd).
have to patch everywhere. want to reduce patch burden.
please accept OS_BSD where OS_LINUX is used in macros.

I have checked that the patches work (entire browser works) on netbsd, and freebsd also uses the same.

What is the expected behavior?

What went wrong?
Lots of files to patch. it hurts.
#if defined(OS_LINUX) everywhere. can we add some || defined(OS_BSD)?

Any part of merging of hundreds files patched (almost all for OS-macros- #if defined(OS_LINUX)) will be welcome and make it easier to keep up to date.

Not sending through the review tool because I don't have a @chromium.org address to use.

Did this work before? N/A 

Chrome version: 56.0.2924.87 (Developer Build) (64-bit)  Channel: n/a
OS Version: 
Flash Version: