Roll src/third_party/webrtc 4f68f5398d7f..f12231d74209 (4 commits)

https://webrtc.googlesource.com/src.git/+log/4f68f5398d7f..f12231d74209

git log 4f68f5398d7f..f12231d74209 --date=short --first-parent --format='%ad %ae %s'
2020-02-06 mmoroz@chromium.org Add wildcard visibility to video_replay to make it buildable in Chromium.
2020-02-06 terelius@webrtc.org Move packet type enum from RtpPacketToSend to rtp_rtcp_defines.h
2020-02-06 sprang@webrtc.org Revert "Remove PlayoutDelayOracle and make RtpSenderVideo guarantee delivery"
2020-02-06 minyue@webrtc.org Add clock skew estimate between sender and receiver in RemoteNtpTimeEstimator.

Created with:
  gclient setdep -r src/third_party/webrtc@f12231d74209

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/webrtc-chromium-autoroll
Please CC webrtc-chromium-sheriffs-robots@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

Bug: chromium:942546
Tbr: webrtc-chromium-sheriffs-robots@google.com
Change-Id: I8fcb60c807f19a03b4379f2761a532373229fb2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2042778Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#739188}

DEPS

@@ -1458,7 +1458,7 @@ deps = {
     Var('chromium_git') + '/external/github.com/gpuweb/cts.git' + '@' + 'ec18cc3262922e7dcdbe70243c6f40606f979144',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '4f68f5398d7fa3d47c449e99893c9bea07bf7ca2',
+    Var('webrtc_git') + '/src.git' + '@' + 'f12231d74209baf159de2c1abfdd764e28dd613b',
 
   'src/third_party/libgifcodec':
      Var('skia_git') + '/libgifcodec' + '@'+  Var('libgifcodec_revision'),