Fix msan flake in rtcstats_integrationtest.cc.

Fix msan flake in rtcstats_integrationtest.cc.

This CL https://codereview.webrtc.org/2641763003 changed echo return
loss /...enhancement stats from being optional to being undefined
because that was the observed behavior (and a TODO was added to
investigate why).

It turns out that these stats are sometimes available, e.g. if the test
runs for a while like MSAN bot does, so this turned the test flaky.
Example failure:
https://build.chromium.org/p/client.webrtc/builders/Linux%20MSan/builds/8242

This CL reverts that change without reverting the rest of the CL which
other CLs depend on, and updates the TODO.

BUG=chromium:627816
TBR=hta@webrtc.org
NOTRY=True
NOPRESUBMIT=True

Review-Url: https://codereview.webrtc.org/2640743007
Cr-Commit-Position: refs/heads/master@{#16187}
Committed: https://chromium.googlesource.com/external/webrtc/+/2d4d653e1fd25ade9ae768058b1225e6b430bc76

[hbos, 2017-01-20 12:15:23]

Patchset #1 (id:1) has been deleted

[hbos, 2017-01-20 12:16:23]

Description was changed from

==========
Fix msan flake in rtcstats_integrationtest.cc.

This CL https://codereview.webrtc.org/2641763003 changed echo return
loss /...enhancement stats from being optional to being undefined
because that was the observed behavior (and a TODO was added to
investigate why).

It turns out that these stats are sometimes available, e.g. if the test
runs for a while like MSAN bot does, so this turned the test flaky.
Example failure:
https://build.chromium.org/p/client.webrtc/builders/Linux%20MSan/builds/8242

This CL reverts that change without reverting the rest of the CL which
other CLs depend on.

BUG=chromium:627816
TBR=hta@webrtc.org
NOTRY=True
NOPRESUBMIT=True
==========

to

==========
Fix msan flake in rtcstats_integrationtest.cc.

This CL https://codereview.webrtc.org/2641763003 changed echo return
loss /...enhancement stats from being optional to being undefined
because that was the observed behavior (and a TODO was added to
investigate why).

It turns out that these stats are sometimes available, e.g. if the test
runs for a while like MSAN bot does, so this turned the test flaky.
Example failure:
https://build.chromium.org/p/client.webrtc/builders/Linux%20MSan/builds/8242

This CL reverts that change without reverting the rest of the CL which
other CLs depend on, and updates the TODO.

BUG=chromium:627816
TBR=hta@webrtc.org
NOTRY=True
NOPRESUBMIT=True
==========

[hbos, 2017-01-20 12:16:26]

The CQ bit was checked by hbos@webrtc.org

[commit-bot: I haz the power, 2017-01-20 12:16:37]

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, 2017-01-20 12:16:42]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1484914586279130,
"parent_rev": "c854ac3755932ea79ac8791ee2fa21e64e6c7826", "commit_rev":
"2d4d653e1fd25ade9ae768058b1225e6b430bc76"}

[commit-bot: I haz the power, 2017-01-20 12:16:44]

Description was changed from

==========
Fix msan flake in rtcstats_integrationtest.cc.

This CL https://codereview.webrtc.org/2641763003 changed echo return
loss /...enhancement stats from being optional to being undefined
because that was the observed behavior (and a TODO was added to
investigate why).

It turns out that these stats are sometimes available, e.g. if the test
runs for a while like MSAN bot does, so this turned the test flaky.
Example failure:
https://build.chromium.org/p/client.webrtc/builders/Linux%20MSan/builds/8242

This CL reverts that change without reverting the rest of the CL which
other CLs depend on, and updates the TODO.

BUG=chromium:627816
TBR=hta@webrtc.org
NOTRY=True
NOPRESUBMIT=True
==========

to

==========
Fix msan flake in rtcstats_integrationtest.cc.

This CL https://codereview.webrtc.org/2641763003 changed echo return
loss /...enhancement stats from being optional to being undefined
because that was the observed behavior (and a TODO was added to
investigate why).

It turns out that these stats are sometimes available, e.g. if the test
runs for a while like MSAN bot does, so this turned the test flaky.
Example failure:
https://build.chromium.org/p/client.webrtc/builders/Linux%20MSan/builds/8242

This CL reverts that change without reverting the rest of the CL which
other CLs depend on, and updates the TODO.

BUG=chromium:627816
TBR=hta@webrtc.org
NOTRY=True
NOPRESUBMIT=True

Review-Url: https://codereview.webrtc.org/2640743007
Cr-Commit-Position: refs/heads/master@{#16187}
Committed:
https://chromium.googlesource.com/external/webrtc/+/2d4d653e1fd25ade9ae768058...
==========

[commit-bot: I haz the power, 2017-01-20 12:16:46]

Committed patchset #1 (id:20001) as
https://chromium.googlesource.com/external/webrtc/+/2d4d653e1fd25ade9ae768058...