Roll src/third_party/webrtc 2bd85ab03921..873610ca688a (2 commits)

https://webrtc.googlesource.com/src.git/+log/2bd85ab03921..873610ca688a

git log 2bd85ab03921..873610ca688a --date=short --first-parent --format='%ad %ae %s'
2020-01-03 mirtad@webrtc.org Fix updating degradation preference in SetRtpParameters.
2020-01-03 saza@webrtc.org Remove one acquisition of capture lock in APM AudioFrame API

Created with:
  gclient setdep -r src/third_party/webrtc@873610ca688a

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: None
Tbr: webrtc-chromium-sheriffs-robots@google.com
Change-Id: I3e102cdd0b959e6d9c0e11016b355a4c59a85338
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1986766Reviewed-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@{#728192}

DEPS

@@ -1494,7 +1494,7 @@ deps = {
     Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + '53655df4cde60b121fc530842ba9a6d5dfec1ae1',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '2bd85ab03921101da5807e0e40c545b5d7ed22ba',
+    Var('webrtc_git') + '/src.git' + '@' + '873610ca688a6db70280ddeff7d220c047c07e99',
 
   'src/third_party/libgifcodec':
      Var('skia_git') + '/libgifcodec' + '@'+  Var('libgifcodec_revision'),