GitLab

* Delete java_warnings_as_errors
* Use treat_warnings_as_errors for android rules
  * warnings-as-errors is now default true for debug builds
* Add --warnings-as-errors to proguard.py, dex.py, bytecode_processor.py
  so that these warnings can all be turned off locally.
* Made build_utils.CheckOutput fail by default when stderr or stdout is
  printed. This should prevent build logs from creaping in.
* Added "you should use treat_warnings_as_errors=false" into error
  message when builds fail due to warnings.

Bug: 1029357
Change-Id: Ia69e545a110554d76e190cb2da8b20fe10d4d6e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2232809Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790225}