[logging] Add LOG_TO_STDERR logging destination

* Separate LOG_TO_SYSTEM_DEBUG_LOG into two cases, LOG_TO_STDERR and
  LOG_TO_SYSTEM_DEBUG_LOG as before.
* Provide the option to only write to system specific logs, write to
  stderr or both, reducing redundant logs for systems which have log
  services, such as with Fuchsia.
* For all systems, logs with severity ERROR and above will continue to
  be written to stderr.
* All systems except Fuchsia have the same behaviour and defaults as
  before.
* Update default logging destination for Fuchsia to system logs only.


Bug: 960882
Change-Id: Ib0f27d194226ac5584609a3e8e4bc561828deed8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1601467
Commit-Queue: Sharon Yang <yangsharon@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#661446}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7cb919a9b3f78d642f8a98e8a81140ef13e2fec2
1 file changed