chromium/try_warmer recipe and linux-warmed trybot spec

chromium/try_warmer recipe takes in a builder_to_warm input and triggers
an led task to run that builder in try, without a patch. It's hard-coded
to only run luci.chromium.try builders at the moment.

led tasks are set to expire after pending for 10 minutes.

linux-warmed is mirroring Linux Builder. The 1149606 bug discusses
using linux_chromium_compile_dbg_ng for this experiment, but it might be
more convenient to do a linux-rel type of builder since our other
experiments are also mirroring Linux Builder.

example try_warmer build:
https://ci.chromium.org/swarming/task/5033944b08358211?server=chromium-swarm.appspot.com

example triggered warm task:
https://chromium-swarm.appspot.com/task?id=5015bc8a2f5a2310

Bug: 1149606
Change-Id: Idc918e3c7f1c08b5cbafbd874e9cf7abe5bf0db0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/2553211
Commit-Queue: Stephanie Kim <kimstephanie@google.com>
Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
17 files changed
tree: f4170c52b77013048998a8027294f9b68513da19
  1. infra/
  2. recipes/
  3. scripts/
  4. site_config/
  5. third_party/
  6. .gitattributes
  7. .gitignore
  8. .style.yapf
  9. .vpython
  10. .yapfignore
  11. codereview.settings
  12. CROS_OWNERS
  13. DEPS
  14. environment.cfg.py
  15. LICENSE
  16. OWNERS
  17. PRESUBMIT.py
  18. README.md
  19. WATCHLISTS
README.md

Recipes

If you're here to make a change to ‘recipes’ (the code located in scripts/slave/recipes*), please take a look at the README for more information pertaining to recipes.

Style

The preferred style is PEP8 with two-space indent; that is, the Chromium Python style. Functions use lowercase_with_underscores, with the exception of the special functions RunSteps and RunTests in recipes. Use yapf (git cl format --no-clang-format) to autoformat new code.