Revert of Fix potential shutdown deadlock in UI service

Revert of Fix potential shutdown deadlock in UI service (patchset #2 id:20001 of https://codereview.chromium.org/2651443002/ )

Reason for revert:
Bisect by tzik@ suggests it could be the culprit for tsan builder failing, e.g. https://uberchromegw.corp.google.com/i/chromium.memory/builders/Linux%20TSan%20Tests/builds/581/steps/content_browsertests/logs/RenderThreadImplBrowserTest.InputHandlerManagerDestroyedAfterCompositorThread

Original issue's description:
> Fix potential shutdown deadlock in UI service
> 
> If the GpuPtr is disconnected while there are pending buffer allocations
> in flight, this can lead to the main thread deadlocking on a WaitableEvent
> that never signals.
> 
> Fixes that by tracking pending allocations and ensuring they're always
> signalled on connection error or other shutdown events.
> 
> BUG=
> R=sadrul@chromium.org
> 
> Review-Url: https://codereview.chromium.org/2651443002
> Cr-Commit-Position: refs/heads/master@{#445434}
> Committed: https://chromium.googlesource.com/chromium/src/+/d0e46de3ff797f53376fa63297a5d41241568fdf

TBR=sadrul@chromium.org,rockot@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=685157

[mastiz, 2017-01-25 14:49:20]

The CQ bit was checked by mastiz@chromium.org

[mastiz, 2017-01-25 14:49:20]

Created Revert of Fix potential shutdown deadlock in UI service

[commit-bot: I haz the power, 2017-01-25 14:49:30]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[mastiz, 2017-01-25 14:49:42]

Description was changed from

==========
Revert of Fix potential shutdown deadlock in UI service (patchset #2 id:20001 of
https://codereview.chromium.org/2651443002/ )

Reason for revert:
Bisect by tzik@ suggests it could be the culprit for tsan builder failing, e.g.
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Linux%20TSan%...

Original issue's description:
> Fix potential shutdown deadlock in UI service
> 
> If the GpuPtr is disconnected while there are pending buffer allocations
> in flight, this can lead to the main thread deadlocking on a WaitableEvent
> that never signals.
> 
> Fixes that by tracking pending allocations and ensuring they're always
> signalled on connection error or other shutdown events.
> 
> BUG=
> R=sadrul@chromium.org
> 
> Review-Url: https://codereview.chromium.org/2651443002
> Cr-Commit-Position: refs/heads/master@{#445434}
> Committed:
https://chromium.googlesource.com/chromium/src/+/d0e46de3ff797f53376fa63297a5...

TBR=sadrul@chromium.org,rockot@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=
==========

to

==========
Revert of Fix potential shutdown deadlock in UI service (patchset #2 id:20001 of
https://codereview.chromium.org/2651443002/ )

Reason for revert:
Bisect by tzik@ suggests it could be the culprit for tsan builder failing, e.g.
https://uberchromegw.corp.google.com/i/chromium.memory/builders/Linux%20TSan%...

Original issue's description:
> Fix potential shutdown deadlock in UI service
> 
> If the GpuPtr is disconnected while there are pending buffer allocations
> in flight, this can lead to the main thread deadlocking on a WaitableEvent
> that never signals.
> 
> Fixes that by tracking pending allocations and ensuring they're always
> signalled on connection error or other shutdown events.
> 
> BUG=
> R=sadrul@chromium.org
> 
> Review-Url: https://codereview.chromium.org/2651443002
> Cr-Commit-Position: refs/heads/master@{#445434}
> Committed:
https://chromium.googlesource.com/chromium/src/+/d0e46de3ff797f53376fa63297a5...

TBR=sadrul@chromium.org,rockot@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=685157
==========

[mastiz, 2017-01-25 14:49:51]

The CQ bit was unchecked by mastiz@chromium.org

[mastiz, 2017-01-25 14:49:57]

The CQ bit was checked by mastiz@chromium.org

[commit-bot: I haz the power, 2017-01-25 14:50:00]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Ken Rockot(use gerrit already), 2017-01-25 15:07:38]

On 2017/01/25 at 14:50:00, commit-bot wrote:
> CQ is trying da patch. Follow status at
>  
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

We generally do not revert for non-tree-closing issues. This CL can't be
reverted as-is because there are dependent patches which have since landed.

It's been on ToT for at least a day, so I will take a look at it over the next
hour and prepare a fix if it is indeed the culprit.

[mastiz, 2017-01-25 15:23:55]

The CQ bit was unchecked by mastiz@chromium.org