Avoid data race in RtcpReceiver.

Avoid data race in RtcpReceiver.

See eg https://build.chromium.org/p/client.webrtc/builders/Linux%20Tsan%20v2/builds/3930/steps/video_engine_tests/logs/stdio

Also some cleanup, lock annotations.

BUG=

Committed: https://crrev.com/7dc39f331a161a24a4d4c6aac7cfb6850f43fb56
Cr-Commit-Position: refs/heads/master@{#10266}

[sprang_webrtc, 2015-10-09 08:29:39]

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

[pbos-webrtc, 2015-10-09 09:50:52]

lgtm woo

https://codereview.webrtc.org/1401463003/diff/1/webrtc/modules/rtp_rtcp/sourc...
File webrtc/modules/rtp_rtcp/source/rtcp_receiver.h (right):

https://codereview.webrtc.org/1401463003/diff/1/webrtc/modules/rtp_rtcp/sourc...
webrtc/modules/rtp_rtcp/source/rtcp_receiver.h:138: 
git cl format

[sprang_webrtc, 2015-10-09 11:18:44]

https://codereview.webrtc.org/1401463003/diff/1/webrtc/modules/rtp_rtcp/sourc...
File webrtc/modules/rtp_rtcp/source/rtcp_receiver.h (right):

https://codereview.webrtc.org/1401463003/diff/1/webrtc/modules/rtp_rtcp/sourc...
webrtc/modules/rtp_rtcp/source/rtcp_receiver.h:138: 
On 2015/10/09 09:50:52, pbos-webrtc wrote:
> git cl format

Fixed. For some reason this was not caught by git cl format...

[sprang_webrtc, 2015-10-09 11:18:53]

The CQ bit was checked by sprang@webrtc.org

[sprang_webrtc, 2015-10-09 11:18:53]

The patchset sent to the CQ was uploaded after l-g-t-m from pbos@webrtc.org
Link to the patchset: https://codereview.webrtc.org/1401463003/#ps20001 (title:
"Formatting")

[commit-bot: I haz the power, 2015-10-09 11:19:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1401463003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1401463003/20001

[commit-bot: I haz the power, 2015-10-09 11:24:22]

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

[commit-bot: I haz the power, 2015-10-09 11:24:23]

Try jobs failed on following builders:
  presubmit on tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/presubmit/builds/1173)

[sprang_webrtc, 2015-10-09 12:06:51]

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

[sprang_webrtc, 2015-10-09 12:06:52]

+stefan as owner.

[stefan-webrtc, 2015-10-13 15:00:33]

lgtm

[sprang_webrtc, 2015-10-13 15:01:52]

The CQ bit was checked by sprang@webrtc.org

[commit-bot: I haz the power, 2015-10-13 15:02:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1401463003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1401463003/20001

[commit-bot: I haz the power, 2015-10-13 16:17:54]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-13 16:18:04]

Patchset 2 (id:??) landed as
https://crrev.com/7dc39f331a161a24a4d4c6aac7cfb6850f43fb56
Cr-Commit-Position: refs/heads/master@{#10266}