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This is a reland of 2db41802

This CL will not schedule builds on the bots initially. This will let
me test what's going wrong without breaking the waterfall and confusing
sheriffs.

Original change's description:
> Add debug chromium bots
>
> These are mirrors of the existing release bots
>
> Bug: 867725
> Change-Id: I6f59d04a82103572e801273e294534e822d3e03d
> Reviewed-on: https://chromium-review.googlesource.com/1159172
> Commit-Queue: Stephen Martinis <martiniss@chromium.org>
> Reviewed-by: Nodir Turakulov <nodir@chromium.org>
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Reviewed-by: Kenneth Russell <kbr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#582390}

Bug: 867725
Change-Id: Ic401e310241bb986f3fbba4666e2e9bfa191be5a
Reviewed-on: https://chromium-review.googlesource.com/1184120
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585600}