Revert of New task queueing primitive for async tasks: TaskQueue.

Revert of New task queueing primitive for async tasks: TaskQueue. (patchset #8 id:330001 of https://codereview.webrtc.org/1927133004/ )

Reason for revert:
sigh.  Have to revert again as there seems to have have been some change made for pnacl and CrOS.

Original issue's description:
> Reland of New task queueing primitive for async tasks: TaskQueue. (patchset #1 id:1 of https://codereview.webrtc.org/1935483002/ )
>
> New task queueing primitive for async tasks: TaskQueue.
> TaskQueue is a new way to asynchronously execute tasks sequentially
> in a thread safe manner with minimal locking.  The implementation
> uses OS supported APIs to do this that are compatible with async IO
> notifications from things like sockets and files.
>
> This class is a part of rtc_base_approved, so can be used by both
> the webrtc and libjingle parts of the WebRTC library.  Moving forward,
> we can replace rtc::Thread and webrtc::ProcessThread with this implementation.
>
> NOTE: It should not be assumed that all tasks that execute on a TaskQueue,
> run on the same thread.  E.g. on Mac and iOS, we use GCD dispatch queues
> which means that tasks might execute on different threads depending on
> what's the most efficient thing to do.
>
> TBR=perkj@webrtc.org
>
> Committed: https://crrev.com/65d1f2aba216d077c6d22488f03e56984aef1c68
> Cr-Commit-Position: refs/heads/master@{#12737}

TBR=perkj@webrtc.org,phoglund@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/3f90087ce8dccd0005a6c1589d34ef98486775f1
Cr-Commit-Position: refs/heads/master@{#12738}

[tommi, 2016-05-13 21:33:20]

Created Revert of New task queueing primitive for async tasks: TaskQueue.

[commit-bot: I haz the power, 2016-05-13 21:33:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1981573002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1981573002/1

[commit-bot: I haz the power, 2016-05-13 21:33:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-05-13 21:33:48]

Description was changed from

==========
Revert of New task queueing primitive for async tasks: TaskQueue. (patchset #8
id:330001 of https://codereview.webrtc.org/1927133004/ )

Reason for revert:
sigh.  Have to revert again as there seems to have have been some change made
for pnacl and CrOS.

Original issue's description:
> Reland of New task queueing primitive for async tasks: TaskQueue. (patchset #1
id:1 of https://codereview.webrtc.org/1935483002/ )
> 
> New task queueing primitive for async tasks: TaskQueue.
> TaskQueue is a new way to asynchronously execute tasks sequentially
> in a thread safe manner with minimal locking.  The implementation
> uses OS supported APIs to do this that are compatible with async IO
> notifications from things like sockets and files.
> 
> This class is a part of rtc_base_approved, so can be used by both
> the webrtc and libjingle parts of the WebRTC library.  Moving forward,
> we can replace rtc::Thread and webrtc::ProcessThread with this implementation.
> 
> NOTE: It should not be assumed that all tasks that execute on a TaskQueue,
> run on the same thread.  E.g. on Mac and iOS, we use GCD dispatch queues
> which means that tasks might execute on different threads depending on
> what's the most efficient thing to do.
> 
> TBR=perkj@webrtc.org
> 
> Committed: https://crrev.com/65d1f2aba216d077c6d22488f03e56984aef1c68
> Cr-Commit-Position: refs/heads/master@{#12737}

TBR=perkj@webrtc.org,phoglund@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
==========

to

==========
Revert of New task queueing primitive for async tasks: TaskQueue. (patchset #8
id:330001 of https://codereview.webrtc.org/1927133004/ )

Reason for revert:
sigh.  Have to revert again as there seems to have have been some change made
for pnacl and CrOS.

Original issue's description:
> Reland of New task queueing primitive for async tasks: TaskQueue. (patchset #1
id:1 of https://codereview.webrtc.org/1935483002/ )
>
> New task queueing primitive for async tasks: TaskQueue.
> TaskQueue is a new way to asynchronously execute tasks sequentially
> in a thread safe manner with minimal locking.  The implementation
> uses OS supported APIs to do this that are compatible with async IO
> notifications from things like sockets and files.
>
> This class is a part of rtc_base_approved, so can be used by both
> the webrtc and libjingle parts of the WebRTC library.  Moving forward,
> we can replace rtc::Thread and webrtc::ProcessThread with this implementation.
>
> NOTE: It should not be assumed that all tasks that execute on a TaskQueue,
> run on the same thread.  E.g. on Mac and iOS, we use GCD dispatch queues
> which means that tasks might execute on different threads depending on
> what's the most efficient thing to do.
>
> TBR=perkj@webrtc.org
>
> Committed: https://crrev.com/65d1f2aba216d077c6d22488f03e56984aef1c68
> Cr-Commit-Position: refs/heads/master@{#12737}

TBR=perkj@webrtc.org,phoglund@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/3f90087ce8dccd0005a6c1589d34ef98486775f1
Cr-Commit-Position: refs/heads/master@{#12738}
==========

[commit-bot: I haz the power, 2016-05-13 21:33:48]

Patchset 1 (id:??) landed as
https://crrev.com/3f90087ce8dccd0005a6c1589d34ef98486775f1
Cr-Commit-Position: refs/heads/master@{#12738}

[tommi, 2016-05-14 13:00:22]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.webrtc.org/1984503002/ by tommi@webrtc.org.

The reason for reverting is: Reland of New task queueing primitive for async
tasks: TaskQueue..