Reland of landing: Implement RTCConfiguration.iceCandidatePoolSize.

Reland: Implement RTCConfiguration.iceCandidatePoolSize. (https://codereview.webrtc.org/1956453003/ )

> Original issue's description:
> > Relanding: Implement RTCConfiguration.iceCandidatePoolSize.
> > 
> > Depends on this CL in order to work in Chromium:
> > https://codereview.chromium.org/1976673002/
> > 
> > It works by creating pooled PortAllocatorSessions which can be picked up
> > by a P2PTransportChannel when needed (after a local description is set).
> > 
> > This can optimize candidate gathering time when there is some time between
> > creating a PeerConnection and setting a local description.
> > 
> > R=pthatcher@webrtc.org
> > 
> > Committed: https://chromium.googlesource.com/external/webrtc/+/48e9d05f510b1616c81303944008f75825971802
> > 
> > Committed: https://crrev.com/a1c303535fe7a29b87879047996efa2952f9701b
> > Cr-Commit-Position: refs/heads/master@{#12729}

TBR=pthatcher@webrtc.org,honghaiz@webrtc.org,deadbeef@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.

[tommi, 2016-05-16 18:52:27]

Created Reland of landing: Implement RTCConfiguration.iceCandidatePoolSize.

[tommi, 2016-05-16 18:54:01]

Description was changed from

==========
Reland of landing: Implement RTCConfiguration.iceCandidatePoolSize. (patchset #1
id:1 of https://codereview.webrtc.org/1982513002/ )

Reason for revert:
Relanding

Original issue's description:
> Revert of Relanding: Implement RTCConfiguration.iceCandidatePoolSize.
(patchset #7 id:120001 of https://codereview.webrtc.org/1956453003/ )
> 
> Reason for revert:
> Speculative revert to see if this could be triggering an error on the Memcheck
build bot where EndToEndTest.SendsAndReceivesH264 consistently times out:
> 
> https://build.chromium.org/p/client.webrtc/builders/Linux%20Memcheck
> 
> 
> 
> Original issue's description:
> > Relanding: Implement RTCConfiguration.iceCandidatePoolSize.
> > 
> > Depends on this CL in order to work in Chromium:
> > https://codereview.chromium.org/1976673002/
> > 
> > It works by creating pooled PortAllocatorSessions which can be picked up
> > by a P2PTransportChannel when needed (after a local description is set).
> > 
> > This can optimize candidate gathering time when there is some time between
> > creating a PeerConnection and setting a local description.
> > 
> > R=pthatcher@webrtc.org
> > 
> > Committed:
https://chromium.googlesource.com/external/webrtc/+/48e9d05f510b1616c81303944...
> > 
> > Committed: https://crrev.com/a1c303535fe7a29b87879047996efa2952f9701b
> > Cr-Commit-Position: refs/heads/master@{#12729}
> 
> TBR=pthatcher@webrtc.org,honghaiz@webrtc.org,deadbeef@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true

TBR=pthatcher@webrtc.org,honghaiz@webrtc.org,deadbeef@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
==========

to

==========
Reland: Implement RTCConfiguration.iceCandidatePoolSize.
(https://codereview.webrtc.org/1956453003/ )

> Original issue's description:
> > Relanding: Implement RTCConfiguration.iceCandidatePoolSize.
> > 
> > Depends on this CL in order to work in Chromium:
> > https://codereview.chromium.org/1976673002/
> > 
> > It works by creating pooled PortAllocatorSessions which can be picked up
> > by a P2PTransportChannel when needed (after a local description is set).
> > 
> > This can optimize candidate gathering time when there is some time between
> > creating a PeerConnection and setting a local description.
> > 
> > R=pthatcher@webrtc.org
> > 
> > Committed:
https://chromium.googlesource.com/external/webrtc/+/48e9d05f510b1616c81303944...
> > 
> > Committed: https://crrev.com/a1c303535fe7a29b87879047996efa2952f9701b
> > Cr-Commit-Position: refs/heads/master@{#12729}

TBR=pthatcher@webrtc.org,honghaiz@webrtc.org,deadbeef@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
==========

[tommi, 2016-05-16 18:54:07]

The CQ bit was checked by tommi@webrtc.org

[commit-bot: I haz the power, 2016-05-16 18:54:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1984573003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1984573003/1

[commit-bot: I haz the power, 2016-05-16 18:55:23]

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

[commit-bot: I haz the power, 2016-05-16 18:55:24]

Try jobs failed on following builders:
  android_compile_x64_dbg on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/android_compile_x64_dbg...)
  android_gn_rel on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/android_gn_rel/builds/1...)
  linux_asan on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_asan/builds/14753)
  linux_libfuzzer_rel on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_libfuzzer_rel/bui...)
  linux_tsan2 on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_tsan2/builds/12205)
  linux_ubsan_vptr on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_ubsan_vptr/builds...)