Re-land https://codereview.chromium.org/2103043002/

Re-land https://codereview.chromium.org/2103043002/

Cherry-pick buildbot 7d31a0593e2e207289511c10f68a8bc4ba13b759:

document buildbot.db.pool

BUG=620572
Committed: https://chromium.googlesource.com/chromium/tools/build/+/15d137f8b9ab5521db8e7435adf22d5112eb790d

[dsansome, 2016-07-19 01:07:42]

dsansome@chromium.org changed reviewers:
+ stip@chromium.org

[ghost stip (do not use), 2016-07-20 01:59:22]

lgtm

[dsansome, 2016-07-20 03:43:04]

The CQ bit was checked by dsansome@chromium.org

[commit-bot: I haz the power, 2016-07-20 03:43:11]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-20 03:47:04]

Description was changed from

==========
Re-land https://codereview.chromium.org/2103043002/

Cherry-pick buildbot 7d31a0593e2e207289511c10f68a8bc4ba13b759:

document buildbot.db.pool

BUG=620572
==========

to

==========
Re-land https://codereview.chromium.org/2103043002/

Cherry-pick buildbot 7d31a0593e2e207289511c10f68a8bc4ba13b759:

document buildbot.db.pool

BUG=620572

Committed:
https://chromium.googlesource.com/chromium/tools/build/+/15d137f8b9ab5521db8e...
==========

[commit-bot: I haz the power, 2016-07-20 03:47:05]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/tools/build/+/15d137f8b9ab5521db8e...