Sorry for the trouble. I didn't realize there were other build
configurations in need of updates.

Root cause is https://chromium-review.googlesource.com/c/chromium/src/+/1035619 .

This is a product bug and not a bug in CrOS infrastructure. Moving component.

Based on #3, Ken, could you take a look?

I'm happy to help, but I'm not sure I understand the distinction between "product bug" and infra bug in this context.

If the claim is that this is a bug in Chromium, that is incorrect. The bug here is that some builders are now misconfigured.

Can someone from infra at least help me understand where the informational builders get their gclient configs?

I believe you'll find these two files to be relevant:

https://cs.corp.google.com/chromeos_public/chromite/lib/gclient.py
https://cs.corp.google.com/chromeos_public/chromite/scripts/sync_chrome.py

But I don't really understand how they work.

Thanks, looking

It looks like this should do the trick: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1037920

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/dd3fcf9f3eb0e0bea224ea740554904bb6212745

commit dd3fcf9f3eb0e0bea224ea740554904bb6212745
Author: Ken Rockot <rockot@chromium.org>
Date: Wed May 02 00:44:22 2018

Set target_os=['chromeos'] in generated gclient specs

As of CL:1035619, target_os=['chromeos'] is required for checkouts
used to build Chrome for Chrome OS.

BUG= chromium:838608 
TEST=None

Change-Id: I41b72501b2ad3b5f9c5e40796648acc5e9742d88
Reviewed-on: https://chromium-review.googlesource.com/1037920
Trybot-Ready: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Ken Rockot <rockot@chromium.org>
Tested-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>

[modify] https://crrev.com/dd3fcf9f3eb0e0bea224ea740554904bb6212745/lib/gclient_unittest.py
[modify] https://crrev.com/dd3fcf9f3eb0e0bea224ea740554904bb6212745/lib/gclient.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/53fc38c62d5fdde2bf1a2fd775ce657e3788ac75

commit 53fc38c62d5fdde2bf1a2fd775ce657e3788ac75
Author: chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Wed May 02 03:24:05 2018

Roll src/third_party/chromite/ 4736430a2..dd3fcf9f3 (1 commit)

https://chromium.googlesource.com/chromiumos/chromite.git/+log/4736430a2b1c..dd3fcf9f3eb0

$ git log 4736430a2..dd3fcf9f3 --date=short --no-merges --format='%ad %ae %s'
2018-05-01 rockot Set target_os=['chromeos'] in generated gclient specs

Created with:
  roll-dep src/third_party/chromite
BUG= chromium:838608 


The AutoRoll server is located here: https://chromite-chromium-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=chrome-os-gardeners@chromium.org

Change-Id: I770cc7362ad14fc63e8173eeed6661d85b8f4bb1
Reviewed-on: https://chromium-review.googlesource.com/1038821
Reviewed-by: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#555300}
[modify] https://crrev.com/53fc38c62d5fdde2bf1a2fd775ce657e3788ac75/DEPS

Things appear to be turning green! Thanks everyone for helping to figure this out and get the fix landed.

chrome-tot-chromeos-amd64-generic bot seems still have the problem. Is it not using chromite/gclient.py ?

e.g.
https://uberchromegw.corp.google.com/i/chromeos.chrome/builders/chrome-tot-chromeos-amd64-generic/builds/35435

""" to /b/c/b/chrome_tot_chromeos_amd64_generic/src/out_amd64-generic/Release/args.gn.
/b/c/b/chrome_tot_chromeos_amd64_generic/src/buildtools/linux64/gn gen //out_amd64-generic/Release --check
  -> returned 1
ERROR at //build/config/android/config.gni:21:7: Assertion failed.
      assert(checkout_android_native_support,
      ^-----
Missing native Android toolchain support. |target_os| in your .gclient configuration file (in the parent directory of src) must include "android" and/or "chromeos". For example: