Remove NullReceiveStatistics

Remove NullReceiveStatistics
rtcp_sender accepts nullptr as indication statistics shouldn't be used,
Other uses of NullReceiveStatistcs were already deleted.

BUG=webrtc:8016
Review-Url: https://codereview.webrtc.org/2988143002
Cr-Commit-Position: refs/heads/master@{#19197}
Committed: https://chromium.googlesource.com/external/webrtc/+/8a1d2a315fb44a936cdf6eee646b7067e66ee8ea

[danilchap, 2017-07-31 15:38:38]

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

[commit-bot: I haz the power, 2017-07-31 15:38:43]

Dry run: 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, 2017-07-31 16:27:34]

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

[commit-bot: I haz the power, 2017-07-31 16:27:35]

Dry run: This issue passed the CQ dry run.

[danilchap, 2017-07-31 16:32:36]

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

[sprang_webrtc, 2017-08-01 09:53:43]

lgtm

[danilchap, 2017-08-01 10:18:47]

The CQ bit was checked by danilchap@webrtc.org

[commit-bot: I haz the power, 2017-08-01 10:18:56]

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, 2017-08-01 10:21:38]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1501582727736670, "parent_rev":
"d339dbc7d4758e62b02740feda85c82dd6b2eba5", "commit_rev":
"8a1d2a315fb44a936cdf6eee646b7067e66ee8ea"}

[commit-bot: I haz the power, 2017-08-01 10:21:45]

Description was changed from

==========
Remove NullReceiveStatistics
rtcp_sender accepts nullptr as indication statistics shouldn't be used,
Other uses of NullReceiveStatistcs were already deleted.

BUG=webrtc:8016
==========

to

==========
Remove NullReceiveStatistics
rtcp_sender accepts nullptr as indication statistics shouldn't be used,
Other uses of NullReceiveStatistcs were already deleted.

BUG=webrtc:8016

Review-Url: https://codereview.webrtc.org/2988143002
Cr-Commit-Position: refs/heads/master@{#19197}
Committed:
https://chromium.googlesource.com/external/webrtc/+/8a1d2a315fb44a936cdf6eee6...
==========

[commit-bot: I haz the power, 2017-08-01 10:21:47]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/8a1d2a315fb44a936cdf6eee6...