I believe these resources were provided in: 

https://bugs.chromium.org/p/chromium/issues/detail?id=825180#c9

New machines:
swarm77-c7
swarm78-c7
swarm79-c7

So these just need to be represented in the private swarming config file, and the old bots removed (when ready) from the public config file.

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/infradata/config/+/1ec08cce0b83bd51097a8711a969272a6600f38d

commit 1ec08cce0b83bd51097a8711a969272a6600f38d
Author: Nghia Nguyen <nednguyen@google.com>
Date: Tue Apr 10 19:59:47 2018

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/508d135e644dc3042a769e0ccf39d8f9e4eaf380

commit 508d135e644dc3042a769e0ccf39d8f9e4eaf380
Author: Ned Nguyen <nednguyen@google.com>
Date: Tue Apr 10 20:17:19 2018

Update perf ids of machines in 'One Buildbot Step Test Builder'

Bug:830957
Change-Id: Ia977b531e4c12bed0faa9c216754b191d8b3fadb
TBR=eyaich@chromium.org

NOTRY=true  # all tests are in PRESUBMIT

Change-Id: Ia977b531e4c12bed0faa9c216754b191d8b3fadb
Reviewed-on: https://chromium-review.googlesource.com/1005884
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#549627}
[modify] https://crrev.com/508d135e644dc3042a769e0ccf39d8f9e4eaf380/testing/buildbot/chromium.perf.fyi.json
[modify] https://crrev.com/508d135e644dc3042a769e0ccf39d8f9e4eaf380/tools/perf/core/benchmark_sharding_map.json
[modify] https://crrev.com/508d135e644dc3042a769e0ccf39d8f9e4eaf380/tools/perf/core/perf_data_generator.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/build/+/57503d52e255ac00e9212c544f8b7b77dbe1eaf2

commit 57503d52e255ac00e9212c544f8b7b77dbe1eaf2
Author: Nghia Nguyen <nednguyen@google.com>
Date: Wed Apr 11 12:41:45 2018

Switch 'One Buildbot Step Test Builder' to use private swarming server

Bug:830957
Change-Id: I04ce38583b94fecedcc6dad717e49a10b6667fb9
Reviewed-on: https://chromium-review.googlesource.com/1006185
Commit-Queue: Emily Hanley <eyaich@chromium.org>
Reviewed-by: Emily Hanley <eyaich@chromium.org>

[modify] https://crrev.com/57503d52e255ac00e9212c544f8b7b77dbe1eaf2/scripts/slave/recipe_modules/chromium_tests/chromium_perf_fyi.py