The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/build/+/81e97dc776455659acee5dfc96995e6fcd2cd078

commit 81e97dc776455659acee5dfc96995e6fcd2cd078
Author: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Date: Mon Aug 27 01:23:38 2018

Use cbb_goma_client_type instead of cbb_goma_canary.

Due to the regression of crbug.com/876225, cbb_goma_canary is actually
not used.  The fix I have written uses cbb_goma_client_type instead of
cbb_goma_canary:
https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1188202
It should be fine for us to go with cbb_goma_client_type.

Bug:  876585 
Change-Id: I59062f179763bab4b1d31174ea2cd4134011203a
Reviewed-on: https://chromium-review.googlesource.com/1188204
Commit-Queue: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>

[modify] https://crrev.com/81e97dc776455659acee5dfc96995e6fcd2cd078/scripts/slave/recipes/cros/swarming.py
[modify] https://crrev.com/81e97dc776455659acee5dfc96995e6fcd2cd078/scripts/slave/recipes/cros/swarming.expected/goma_canary.json

As far as I know, due to crbug.com/876225, cbb_goma_canary flag seems not be set.  That is why it is fine to submit #1.

To fix this issue, two things remained.
1. update chromite to make cbb_goma_client_type supported.
blocked by https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1180509
2. update luci-scheduler.cfg using the chromite updated in 1.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/16285b48a4d5cc5c467bb59809db939abef8910f

commit 16285b48a4d5cc5c467bb59809db939abef8910f
Author: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Date: Wed Sep 26 03:40:55 2018

support cbb_goma_client_type.

To make builders use arbitrary cipd ref of goma client package,
we need to make cbb_goma_client_type supported.
We may use "candidate" to specify the release candidate, and "latest" to
specify the latest goma client.

Bug:  chromium:876585 , chromium:876225
Change-Id: I57be8633d4727aee6645c57338be6e44d569f531
Reviewed-on: https://chromium-review.googlesource.com/1188202
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Yoshisato Yanagisawa <yyanagisawa@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>

[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/config/chromeos_config.py
[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/lib/request_build.py
[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/scripts/gen_luci_scheduler_unittest.py
[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/scripts/gen_luci_scheduler.py
[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/config/config_dump.json
[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/lib/config_lib.py
[modify] https://crrev.com/16285b48a4d5cc5c467bb59809db939abef8910f/config/luci-scheduler.cfg