Set up linux-rel-orchestrator-pool experimental try builder

This optional try builder will be running for a few days to verify
that the srcless orchestrator builders are able to run using the bots
in the luci.chromium.try.orchestrator pool. It'll be running with 10%
of CQ traffic.

Bug: 1287228
Change-Id: I19ee31cff8824ec299c5b66359cf80a175a027e8
Commit-Queue: Stephanie Kim <>
Reviewed-by: Ben Pastene <>
Cr-Commit-Position: refs/heads/main@{#1007494}
GitOrigin-RevId: 421ac04ec7eb5bdae929a90d7be9e816c5ebae6e
2 files changed
tree: b15d272c9887347540bb396be904b3449f83fde8
  1. docs/
  2. lib/
  3. mb_config_expectations/
  6. mb
  7. mb.bat
  9. mb_config.pyl
  12. OWNERS
  16. rts_banned_suites.json

MB - The Meta-Build wrapper

MB is a simple wrapper around the GN build tool.

It was originally written as part of the GYP->GN migration, in order to provide a uniform interface to either GYP or GN, such that users and bots can call one script and not need to worry about whether a given bot was meant to use GN or GYP.

It eventually grew additional functionality and is now still used even though everything is GN-only.

It supports two main functions:

  1. “gen” - the main gn gen invocation that generates the Ninja files needed for the build.

  2. “analyze” - the step that takes a list of modified files and a list of desired targets and reports which targets will need to be rebuilt.

We also use MB as a forcing function to collect all of the different build configurations that we actually support for Chromium builds into one place, in //tools/mb/mb_config.pyl.

For more information, see: