Refactor ios.trigger() in preparation for migration to chromium_tests.

This CL is intended to be a moderate-sized refactor with no behavior change. The
only major difference is that we no longer try to catch and ignore exceptions in
chromium_swarming.trigger_task(). This reflects the new behavior of the method,
which only raises an exception on unrecoverable error.

This CL contains a slight logic change -- if tasks are not triggered, they are
also not collected.

Everything else is a refactor to explicitly specify state dependencies of
trigger(). This is in preparation of moving the method into a new class [a
subclass of Test].

Tested via LED at:
https://chromium-swarm.appspot.com/task?id=442c77515c140010

Bug:  951182
Change-Id: I964c495c8571be51d595a4ba16891070841ad3cf
Recipe-Manual-Change: build_limited_scripts_slave
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/1566573
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
6 files changed
tree: 1b79a32cf51c636c1193b2adf1ee504e1f8f1f53
  1. infra/
  2. masters/
  3. scripts/
  4. site_config/
  5. slave/
  6. tests/
  7. third_party/
  8. .gitattributes
  9. .gitignore
  10. .vpython
  11. codereview.settings
  12. DEPS
  13. environment.cfg.py
  14. LICENSE
  15. OWNERS
  16. PRESUBMIT.py
  17. README.md
  18. WATCHLISTS
README.md

build

Hi build contributor! If you do any change in scripts/master/ or touching any master's html/ directories, you must restart master.chromium.fyi first and ensure that it still works before restarting other masters.

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.