Remove mutable from rtc::CriticalSections.

Remove mutable from rtc::CriticalSections.

A couple of mutables were added after last removal of mutables, so
removing those. rtc::CriticalSection is const-lockable.

BUG=
R=tommi@webrtc.org

[pbos-webrtc, 2016-02-01 15:37:25]

PTAL, done with regex:

Replacing with 's/mutable rtc::CriticalSection/rtc::CriticalSection/g' in files:

  webrtc/video/call_stats.h
  webrtc/video/encoder_state_feedback.h
  webrtc/video/payload_router.h
  webrtc/video/video_capture_input.h
  webrtc/video/vie_channel.h
  webrtc/video/vie_encoder.h
  webrtc/video/vie_remb.h
  webrtc/voice_engine/channel.h
  webrtc/voice_engine/channel_manager.h
  webrtc/voice_engine/dtmf_inband.h
  webrtc/voice_engine/level_indicator.h
  webrtc/voice_engine/shared_data.h
  webrtc/voice_engine/statistics.h
  webrtc/voice_engine/test/auto_test/fakes/conference_transport.h
  webrtc/voice_engine/test/auto_test/fixtures/after_initialization_fixture.h

[tommi, 2016-02-01 15:59:59]

The CQ bit was checked by tommi@webrtc.org

[tommi, 2016-02-01 16:00:00]

lgtm

[commit-bot: I haz the power, 2016-02-01 16:00:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1652983002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1652983002/1

[commit-bot: I haz the power, 2016-02-01 17:01:04]

Description was changed from

==========
Remove mutable from rtc::CriticalSections.

A couple of mutables were added after last removal of mutables, so
removing those. rtc::CriticalSection is const-lockable.

BUG=
R=tommi@webrtc.org
==========

to

==========
Remove mutable from rtc::CriticalSections.

A couple of mutables were added after last removal of mutables, so
removing those. rtc::CriticalSection is const-lockable.

BUG=
R=tommi@webrtc.org

Committed: https://crrev.com/d8de1154c9dbf73d44a71d09827660c1fe13e2d6
Cr-Commit-Position: refs/heads/master@{#11447}
==========

[commit-bot: I haz the power, 2016-02-01 17:01:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-02-01 17:01:05]

Patchset 1 (id:??) landed as
https://crrev.com/d8de1154c9dbf73d44a71d09827660c1fe13e2d6
Cr-Commit-Position: refs/heads/master@{#11447}