This caused us to lose our gn check certification. :(
Turns out gn check was just ignoring all the header
paths it didn't understand and so gn check passing
for sky wasn't meaning much. I tried to straighten
out some of the mess in this CL, but its going to take
several more rounds of massaging before gn check
passes again. On the bright side (almost) all of
our headers are absolute now. Turns out my script
(attached to the bug) didn't notice ../ includes
but I'll fix that in the next patch.
R=abarth@chromium.org
BUG=435361
Review URL: https://codereview.chromium.org/746023002
Fix (most) generated includes to have gen/ in their path.
This makes it easier to tell where files exist on disk.
Unfortunately I had to leave the old include path
in engine/BUILD.gn to support all the v8 includes
which were too many to deal with in this patch.
It's a little nasty to have the raw build directory
in our include path, but it produces nicer paths.
R=abarth@chromium.org
