Fix crash when all acks in a feedback message arrive too late.

Fix crash when all acks in a feedback message arrive too late.

BUG=b/37279144

Review-Url: https://codereview.webrtc.org/2820353002
Cr-Commit-Position: refs/heads/master@{#17739}
Committed: https://chromium.googlesource.com/external/webrtc/+/80fba25fc394f6a603ef452f6fb0768326079ce8

[stefan-webrtc, 2017-04-18 10:37:20]

stefan@webrtc.org changed reviewers:
+ elad.alon@webrtc.org, terelius@webrtc.org

[stefan-webrtc, 2017-04-18 10:37:20]

I think a crash could happen in a very intricate scenario where a feedback
message contained a number of lost packets, followed by a packet which was sent
on an old transport. In that case, the transport_feedback_vector would only
contain the lost packets with arrival_time_ms == -1, and they would then be
removed by SortPacketFeedbackVector(), so that a crash would happen here:
    aggregated_result =
OnLongFeedbackDelay(sorted_packet_feedback_vector.back().arrival_time_ms);

For the time being I think the best way to handle obscure cases like this is to
simply return early if we get an empty feedback vector, as I'm doing in this
patch.

[terelius, 2017-04-18 11:09:14]

lgtm

[stefan-webrtc, 2017-04-18 12:25:29]

The CQ bit was checked by stefan@webrtc.org

[commit-bot: I haz the power, 2017-04-18 12:25:31]

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, 2017-04-18 12:33:04]

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

[commit-bot: I haz the power, 2017-04-18 12:33:05]

Try jobs failed on following builders:
  linux_asan on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_asan/builds/24038)
  linux_ubsan on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_ubsan/builds/11573)
  linux_ubsan_vptr on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/linux_ubsan_vptr/builds...)

[stefan-webrtc, 2017-04-18 12:53:39]

Add test.

[stefan-webrtc, 2017-04-18 12:54:31]

The CQ bit was checked by stefan@webrtc.org

[stefan-webrtc, 2017-04-18 12:54:31]

The patchset sent to the CQ was uploaded after l-g-t-m from terelius@webrtc.org
Link to the patchset: https://codereview.webrtc.org/2820353002/#ps20001 (title:
"Add test.")

[commit-bot: I haz the power, 2017-04-18 12:54:35]

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, 2017-04-18 13:45:13]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1492520071017590,
"parent_rev": "20acdfea790a25c193d29648220e9167b3537bb3", "commit_rev":
"80fba25fc394f6a603ef452f6fb0768326079ce8"}

[commit-bot: I haz the power, 2017-04-18 13:45:16]

Description was changed from

==========
Fix crash when all acks in a feedback message arrive too late.

BUG=b/37279144
==========

to

==========
Fix crash when all acks in a feedback message arrive too late.

BUG=b/37279144

Review-Url: https://codereview.webrtc.org/2820353002
Cr-Commit-Position: refs/heads/master@{#17739}
Committed:
https://chromium.googlesource.com/external/webrtc/+/80fba25fc394f6a603ef452f6...
==========

[commit-bot: I haz the power, 2017-04-18 13:45:17]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/external/webrtc/+/80fba25fc394f6a603ef452f6...