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For Wayland debugging, it's helpful to add WAYLAND_DEBUG=client to
the lacros environment.

Introduce --lacros-chrome-additional-env to set arbitrary additional
environment variables when launching lacros.

Bug: none
Change-Id: Ie44f4edd80459d606216cab733e99027d42fc986
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2636264Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845052}