GitLab

This reverts commit 6fc1a00b.

Reason for revert: crbug.com/1110742

Original change's description:
> Add flow trace event to WaitableEvent
> 
> Provide more information by adding a trace event to WaitableEvent::Wait.
> Connect WaitableEvent::Signal with the end of WaitableEvent::TimedWait by a flow event.
> 
> Make the implementation of WaitableEvent::Wait cross-platform and move
> it in waitable_event.cc.
> 
> Bug: 1043616
> Change-Id: I07d13d43e951d6fa223202ccd5f6a076559b416f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2267160
> Reviewed-by: Gabriel Charette <gab@chromium.org>
> Reviewed-by: Alexander Timin <altimin@chromium.org>
> Reviewed-by: Albert J. Wong <ajwong@chromium.org>
> Commit-Queue: Karel Král <karelkral@google.com>
> Cr-Commit-Position: refs/heads/master@{#791831}

TBR=ajwong@chromium.org,dcheng@chromium.org,gab@chromium.org,altimin@chromium.org,karelkral@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1043616, 1110742
Change-Id: Ie72c2bef941d9a215d809e553a4b063a320428b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2325379Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792594}