gfx/harfbuzz status as of 2012-08-16:

This directory contains the "harfbuzz-ng" source from the 'master' branch of
git://anongit.freedesktop.org/git/harfbuzz.

UPDATING:

Note that hb-ot-shape-complex-indic-machine.hh and gfx/harfbuzz/src/hb-version.h
are not present in the upstream Git repository. These are 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 these files when updating harfbuzz, and check them in
to the mozilla tree. (This avoids adding the ragel processor to mozilla's build
prerequisites.)

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. It should only need updating when
new source files or exported headers are added in harfbuzz.