The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/41fd785352b3cf3161d2808c3b8689721be9c59b

commit 41fd785352b3cf3161d2808c3b8689721be9c59b
Author: Ningning Xia <nxia@chromium.org>
Date: Sat Dec 03 01:04:37 2016

Move GetBuildbucketClient into generic_stages.

Will create a separate ScheduleSlavesStage for builds using Buildbucket
to schedule slaves. GetBuildbucketClient will be called by SyncStage,
CompeletionStage, BuildStage and ScheduleSlavesStage, so move it into
the super class.

BUG= chromium:671715 
TEST=unit_tests

Change-Id: Ib50e110ca1017b32746ec1b64dff25af51ea59c5
Reviewed-on: https://chromium-review.googlesource.com/417100
Commit-Ready: Ningning Xia <nxia@chromium.org>
Tested-by: Ningning Xia <nxia@chromium.org>
Reviewed-by: Chris Ching <chingcodes@chromium.org>

[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/cbuildbot/stages/completion_stages.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/cbuildbot/stages/generic_stages.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/lib/config_lib.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/cbuildbot/stages/sync_stages_unittest.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/cbuildbot/stages/sync_stages.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/cbuildbot/stages/generic_stages_unittest.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/lib/config_lib_unittest.py
[modify] https://crrev.com/41fd785352b3cf3161d2808c3b8689721be9c59b/cbuildbot/stages/build_stages.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/a73a4e54855374612fe2ec0c614f45ecd82ffe6e

commit a73a4e54855374612fe2ec0c614f45ecd82ffe6e
Author: Ningning Xia <nxia@chromium.org>
Date: Tue Dec 06 23:19:49 2016

Create ScheduleSlavesStage to schedule slaves via Buildbucket.

Create a separate ScheduleSlavesStage to schedule slave builds using
Buildbucket. Move the buildbucket-scheduler related logics from
SyncStage into ScheduleSlavesStage.

BUG= chromium:671715 
TEST=unit_tests

Change-Id: I5ba4e9e7b2b4e5ed8ea41b81688a0d8f7213164e
Reviewed-on: https://chromium-review.googlesource.com/417064
Commit-Ready: Ningning Xia <nxia@chromium.org>
Tested-by: Ningning Xia <nxia@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>

[add] https://crrev.com/a73a4e54855374612fe2ec0c614f45ecd82ffe6e/cbuildbot/stages/scheduler_stages.py
[add] https://crrev.com/a73a4e54855374612fe2ec0c614f45ecd82ffe6e/cbuildbot/stages/scheduler_stages_unittest.py
[modify] https://crrev.com/a73a4e54855374612fe2ec0c614f45ecd82ffe6e/cbuildbot/stages/sync_stages_unittest.py
[modify] https://crrev.com/a73a4e54855374612fe2ec0c614f45ecd82ffe6e/cbuildbot/stages/sync_stages.py
[modify] https://crrev.com/a73a4e54855374612fe2ec0c614f45ecd82ffe6e/cbuildbot/builders/simple_builders.py
[add] https://crrev.com/a73a4e54855374612fe2ec0c614f45ecd82ffe6e/cbuildbot/stages/scheduler_stages_unittest