Reland of Use sched_yield on all POSIX platforms in PlatformThread.

Reland of Use sched_yield on all POSIX platforms in PlatformThread. (patchset #1 id:1 of https://codereview.webrtc.org/2712133003/ )

Reason for revert:
Relanding - using sched_yield() in PlatformThread on all posix platforms.

Original issue's description:
> Revert of Use sched_yield on all POSIX platforms in PlatformThread. (patchset #1 id:1 of https://codereview.webrtc.org/2716683002/ )
> 
> Reason for revert:
> Reverting this change since it didn't affect the perf regressions we were seeing and actually seems to have caused more regressions as per comment in the bug.
> 
> Original issue's description:
> > Use sched_yield on all POSIX platforms in PlatformThread.
> > (not only MacOS)
> > 
> > This is a test to see if perf regressions we're seeing may be related to the use of nanosleep().
> > 
> > BUG=695438
> > TBR=solenberg@webrtc.org
> > 
> > Review-Url: https://codereview.webrtc.org/2716683002 .
> > Cr-Commit-Position: refs/heads/master@{#16807}
> > Committed: https://chromium.googlesource.com/external/webrtc/+/384498abb5a0dc3e871e437e56b4a556c3ec1023
> 
> TBR=solenberg@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=695438
> 
> Review-Url: https://codereview.webrtc.org/2712133003
> Cr-Commit-Position: refs/heads/master@{#16833}
> Committed: https://chromium.googlesource.com/external/webrtc/+/3ba1a8cd1b875dc7bfcb7075fe4f78d0dfe0ff98

TBR=solenberg@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=695438
Review-Url: https://codereview.webrtc.org/2725573002
Cr-Commit-Position: refs/heads/master@{#16899}
Committed: https://chromium.googlesource.com/external/webrtc/+/4974df41838367e4d50c42bef3be121c7ac6e331

[tommi, 2017-02-28 10:22:14]

The CQ bit was checked by tommi@webrtc.org

[tommi, 2017-02-28 10:22:14]

Created Reland of Use sched_yield on all POSIX platforms in PlatformThread.

[commit-bot: I haz the power, 2017-02-28 10:22:25]

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

[the sun, 2017-02-28 10:42:17]

lgtm

[commit-bot: I haz the power, 2017-02-28 11:01:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-28 11:01:33]

Try jobs failed on following builders:
  linux_ubsan_vptr on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_ubsan_vptr/builds...)

[tommi, 2017-02-28 11:04:06]

The CQ bit was checked by tommi@webrtc.org

[commit-bot: I haz the power, 2017-02-28 11:04:17]

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

[commit-bot: I haz the power, 2017-02-28 11:17:33]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488279846383480, "parent_rev":
"fcdd9df78dd056437a6b4b346597fdfaa7ec72f3", "commit_rev":
"4974df41838367e4d50c42bef3be121c7ac6e331"}

[commit-bot: I haz the power, 2017-02-28 11:17:36]

Description was changed from

==========
Reland of Use sched_yield on all POSIX platforms in PlatformThread. (patchset #1
id:1 of https://codereview.webrtc.org/2712133003/ )

Reason for revert:
Relanding - using sched_yield() in PlatformThread on all posix platforms.

Original issue's description:
> Revert of Use sched_yield on all POSIX platforms in PlatformThread. (patchset
#1 id:1 of https://codereview.webrtc.org/2716683002/ )
> 
> Reason for revert:
> Reverting this change since it didn't affect the perf regressions we were
seeing and actually seems to have caused more regressions as per comment in the
bug.
> 
> Original issue's description:
> > Use sched_yield on all POSIX platforms in PlatformThread.
> > (not only MacOS)
> > 
> > This is a test to see if perf regressions we're seeing may be related to the
use of nanosleep().
> > 
> > BUG=695438
> > TBR=solenberg@webrtc.org
> > 
> > Review-Url: https://codereview.webrtc.org/2716683002 .
> > Cr-Commit-Position: refs/heads/master@{#16807}
> > Committed:
https://chromium.googlesource.com/external/webrtc/+/384498abb5a0dc3e871e437e5...
> 
> TBR=solenberg@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=695438
> 
> Review-Url: https://codereview.webrtc.org/2712133003
> Cr-Commit-Position: refs/heads/master@{#16833}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/3ba1a8cd1b875dc7bfcb7075f...

TBR=solenberg@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=695438
==========

to

==========
Reland of Use sched_yield on all POSIX platforms in PlatformThread. (patchset #1
id:1 of https://codereview.webrtc.org/2712133003/ )

Reason for revert:
Relanding - using sched_yield() in PlatformThread on all posix platforms.

Original issue's description:
> Revert of Use sched_yield on all POSIX platforms in PlatformThread. (patchset
#1 id:1 of https://codereview.webrtc.org/2716683002/ )
> 
> Reason for revert:
> Reverting this change since it didn't affect the perf regressions we were
seeing and actually seems to have caused more regressions as per comment in the
bug.
> 
> Original issue's description:
> > Use sched_yield on all POSIX platforms in PlatformThread.
> > (not only MacOS)
> > 
> > This is a test to see if perf regressions we're seeing may be related to the
use of nanosleep().
> > 
> > BUG=695438
> > TBR=solenberg@webrtc.org
> > 
> > Review-Url: https://codereview.webrtc.org/2716683002 .
> > Cr-Commit-Position: refs/heads/master@{#16807}
> > Committed:
https://chromium.googlesource.com/external/webrtc/+/384498abb5a0dc3e871e437e5...
> 
> TBR=solenberg@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=695438
> 
> Review-Url: https://codereview.webrtc.org/2712133003
> Cr-Commit-Position: refs/heads/master@{#16833}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/3ba1a8cd1b875dc7bfcb7075f...

TBR=solenberg@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=695438

Review-Url: https://codereview.webrtc.org/2725573002
Cr-Commit-Position: refs/heads/master@{#16899}
Committed:
https://chromium.googlesource.com/external/webrtc/+/4974df41838367e4d50c42bef...
==========

[commit-bot: I haz the power, 2017-02-28 11:17:39]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/4974df41838367e4d50c42bef...

[danilchap, 2017-02-28 14:20:27]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.webrtc.org/2721893002/ by danilchap@webrtc.org.

The reason for reverting is: breaks linux_ubsan bots..