Jungshik comments on the CL:

"Mike,  the include line has the following:

/b/c/b/chromeos_amd64_generic_chromium_compile_only_ng/.cros_cache/chrome-sdk/tarballs/amd64-generic+9282.0.0+sysroot_chromeos-base_chromeos-chrome.tar.xz/usr/include/harfbuzz

cros_cache/chrome-sdk/tarballs/... is stale / out-dated?    If so, how can it be updated?"

the sysroot tarballs automatically refresh themselves to use the latest versions available.  so if you used the current 9349.0.0, it would contain the latest code.
$ cros chrome-sdk --board=amd64-generic --version=9349.0.0

however, the default version used is not always the latest, but the LKGM.  and in Chromium, that appears to be 9282.0.0:
$ cat src/chromeos/CHROMEOS_LKGM
9282.0.0

so you'll prob want to talk to who ever is responsible for those bots to figure out why they're behind.  i'll cc a few random people in case they know.

Thanks, Mike. At least, we know why. 

All the updates to src/chromeos/CHROMEOS_LKGM have been done automatically ....

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/967393ad8cfd7a7e3a1e034031bc8d1f37bea446

commit 967393ad8cfd7a7e3a1e034031bc8d1f37bea446
Author: Mike Frysinger <vapier@chromium.org>
Date: Thu Mar 09 06:27:45 2017

chrome-sdk: add a debug log when loading the LKGM version

This makes it clear when you run `cros chrome-sdk --debug` where the
exact version information is coming from by default.

BUG= chromium:699525 
TEST=`cros chrome-sdk --debug` logs the file & version

Change-Id: I04a189fbd83a80684f42709a0fec08e212281225
Reviewed-on: https://chromium-review.googlesource.com/450765
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>

[modify] https://crrev.com/967393ad8cfd7a7e3a1e034031bc8d1f37bea446/cli/cros/cros_chrome_sdk.py

Who'd know why LKGM is rather old in src/chromeos/CHROMEOS_LKGM?  It's more than 2 weeks old. 

LKGM is now 9403.0.0 so that the test should pass now. 

As you can see, there were almost daily updates until Feb 14. Then, a more than a month long gap came in. 

March 27: 9403.0.0
Mar 22: 9391.0.0
Feb 14: 9282.0.0
Feb 12: 9276.0.0
Feb 10: 9269.0.0
Feb 9: 9266.0.0

Just out of curiosity, is there a reason for this change in the interval? 

Ok. Dominik's CL got landed 3 days ago. So, this issue is resolved. Nonetheless, I'm a bit curious about LKGM update interval. :-)