Reland "Pass --xctest to WebRTC iOS tests."

This is a reland of 498ff2fb080dfa2f8f68c1d7a7a3cedbb6c101b6

I have added --undefok to signal absl/flags (used by WebRTC) that
it is fine if --enable-run-ios-unittests-with-xctest is not defined
in the binary (absl/flags doesn't allow to define flags with "-"
in them so WebRTC will just default to link the XCTest runner if this
works).

Original change's description:
> Pass --xctest to WebRTC iOS tests.
>
> This should allow to run GUnit tests as XCtests, some WebRTC tests will
> need to be fixed but this might be a good first step.
>
> Bug: webrtc:12134
> Change-Id: I2a88d76556da24c5e60feee3decad6201f13a8c3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/2541723
> Reviewed-by: Zhaoyang Li <zhaoyangli@chromium.org>
> Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>

TBR=zhaoyangli@chromium.org
Bug: webrtc:12134
Change-Id: I9c29e23523d3e23a1e7813c3575e48503d8c6dc2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/2550656
Reviewed-by: Mirko Bonadei <mbonadei@chromium.org>
Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
8 files changed
tree: 180419a3a4a93549186a62981b4d54fbe8645ffe
  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

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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.