GitLab

This is a step forward to remove the waitable event.
This CL is removing the Waitable event member and reducing
its scope only to the destructor (where it is used).

R=gab@chromium.org

Bug: 1065004
Change-Id: I7a813c09a52ccd428c64631bd81fc8a5d710c880
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2132766Reviewed-by: Maksim Orlovich <morlovich@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756335}