Fix race condition in EndToEndTest.AssignsTransportSequenceNumbers

Fix race condition in EndToEndTest.AssignsTransportSequenceNumbers

Don't verify increasing sequence numbers after test complesion as this
can be racy with regards to test shutting down send transports.

BUG=4894
R=stefan@webrtc.org

Committed: https://chromium.googlesource.com/external/webrtc/+/8d62971611bac3e19d4489427a4b8346ad1e4ca8

[sprang_webrtc, 2015-08-04 08:36:48]

The CQ bit was checked by sprang@webrtc.org

[commit-bot: I haz the power, 2015-08-04 08:36:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1269743004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1269743004/1

[commit-bot: I haz the power, 2015-08-04 08:36:59]

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

[commit-bot: I haz the power, 2015-08-04 08:37:00]

No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
Even if an L-G-T-M may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[sprang_webrtc, 2015-08-04 08:37:23]

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

[commit-bot: I haz the power, 2015-08-04 08:37:28]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1269743004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1269743004/1

[sprang_webrtc, 2015-08-04 08:37:52]

sprang@webrtc.org changed reviewers:
+ stefan@webrtc.org

[stefan-webrtc, 2015-08-04 08:44:59]

lgtm

[commit-bot: I haz the power, 2015-08-04 10:37:36]

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

[commit-bot: I haz the power, 2015-08-04 10:37:36]

Dry run: Try jobs failed on following builders:
  mac_baremetal on tryserver.webrtc (JOB_TIMED_OUT, no build URL)

[sprang_webrtc, 2015-08-04 11:00:40]

The CQ bit was checked by sprang@webrtc.org

[commit-bot: I haz the power, 2015-08-04 11:00:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1269743004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1269743004/1

[commit-bot: I haz the power, 2015-08-04 13:00:57]

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

[commit-bot: I haz the power, 2015-08-04 13:00:58]

Try jobs failed on following builders:
  mac_baremetal on tryserver.webrtc (JOB_TIMED_OUT, no build URL)

[sprang_webrtc, 2015-08-04 14:24:20]

Committed patchset #1 (id:1) manually as
8d62971611bac3e19d4489427a4b8346ad1e4ca8 (presubmit successful).