GitLab

This reverts commit f7da13a2.

Reason for revert: As per comments by Findit

Original change's description:
> [MessageLoop] Lock-free ScheduleWork() scheme
> 
> The Lock is causing hangs because of priority inversion
> mixed with priority boosting (ScheduleWork() tends to
> boost the destination thread which may deschedule the
> posting thread; if the posting thread is a background
> thread this boost-induded-desched-while-holding-lock
> can cause a livelock). See https://crbug.com/890978#c10
> for example crashes catching this.
> 
> The Lock was only necessary for startup/shutdown and is
> being replaced by a lock-free atomic scheme in this CL.
> 
> MessagePump::ScheduleWork() itself was already thread-safe
> (but the Android impl did unnecessarily check a non-atomic bool)
> 
> This adds a WaitableEvent in ~MessageLoop(); hence the requirement
> for a wait-allowance in net's EmbeddedTestServer.
> 
> TBR=zhongyi@chromium.org (embedded_test_server.cc side-effects)
> 
> Bug: 890978, 874237
> Change-Id: I0916e5a99035a935b0a23a770af256f334e78c43
> Reviewed-on: https://chromium-review.googlesource.com/c/1278631
> Commit-Queue: Gabriel Charette <gab@chromium.org>
> Reviewed-by: François Doray <fdoray@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#601600}

TBR=gab@chromium.org,fdoray@chromium.org,zhongyi@chromium.org

Change-Id: I521ef6ba2758f84d13a4f98d65cb41b276cb115e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 890978, 874237
Reviewed-on: https://chromium-review.googlesource.com/c/1294717Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601731}