gfx/harfbuzz status as of 2015-04-25:

This directory contains the harfbuzz source from the 'master' branch of
https://github.com/behdad/harfbuzz.

UPDATING:

Note that gfx/harfbuzz/src/hb-version.h is not present in the upstream Git
repository. It is created at build time by the harfbuzz build system;
but as we don't use that build system in mozilla, it is necessary to refresh
this files when updating harfbuzz, and check them into the mozilla tree.

The normal approach to updating harfbuzz, therefore, is to pull the latest HB
source into a scratch directory and do a local build; then copy the original
sources AND the generated headers mentioned above from the build directory into
the mozilla tree.

In addition, the src/Makefile.in file here is NOT from upstream, nor is it
generated from src/Makefile.am (the original harfbuzz version); it is a mozilla-
specific makefile that is maintained by hand.