RTCStatsCollector: Remove closed channels from opened set.

RTCStatsCollector: Remove closed channels from opened set.

This is a problem if a data channel is re-opened or a new data channel
occupies the same space in memory as a previously closed data channel.

Unittest updated to cover this (failed before fix, now passes).

BUG=webrtc:7181
Review-Url: https://codereview.webrtc.org/2746393003
Cr-Commit-Position: refs/heads/master@{#17304}
Committed: https://chromium.googlesource.com/external/webrtc/+/5bf9def61b916477898dd1d33f0f34b2c8df7056

[hbos, 2017-03-14 11:47:25]

The CQ bit was checked by hbos@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-14 11:47:29]

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

[hbos, 2017-03-14 11:50:49]

hbos@webrtc.org changed reviewers:
+ guidou@webrtc.org

[hbos, 2017-03-14 11:50:49]

Please take a look, guidou.

[commit-bot: I haz the power, 2017-03-14 12:17:25]

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

[commit-bot: I haz the power, 2017-03-14 12:17:26]

Dry run: This issue passed the CQ dry run.

[guidou, 2017-03-20 09:48:44]

lgtm

[hbos, 2017-03-20 09:50:56]

The CQ bit was checked by hbos@webrtc.org

[commit-bot: I haz the power, 2017-03-20 09:50:59]

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, 2017-03-20 10:14:14]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490003456180470, "parent_rev":
"1973ba6ef4909aad7c8bce307d8bf4180ce677fe", "commit_rev":
"5bf9def61b916477898dd1d33f0f34b2c8df7056"}

[commit-bot: I haz the power, 2017-03-20 10:14:17]

Description was changed from

==========
RTCStatsCollector: Remove closed channels from opened set.

This is a problem if a data channel is re-opened or a new data channel
occupies the same space in memory as a previously closed data channel.

Unittest updated to cover this (failed before fix, now passes).

BUG=webrtc:7181
==========

to

==========
RTCStatsCollector: Remove closed channels from opened set.

This is a problem if a data channel is re-opened or a new data channel
occupies the same space in memory as a previously closed data channel.

Unittest updated to cover this (failed before fix, now passes).

BUG=webrtc:7181

Review-Url: https://codereview.webrtc.org/2746393003
Cr-Commit-Position: refs/heads/master@{#17304}
Committed:
https://chromium.googlesource.com/external/webrtc/+/5bf9def61b916477898dd1d33...
==========

[commit-bot: I haz the power, 2017-03-20 10:14:18]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/5bf9def61b916477898dd1d33...