Roll src/third_party/webrtc 1b8ef63876eb..f7f7cc93aa44 (4 commits)

https://webrtc.googlesource.com/src.git/+log/1b8ef63876eb..f7f7cc93aa44

git log 1b8ef63876eb..f7f7cc93aa44 --date=short --first-parent --format='%ad %ae %s'
2020-04-27 jonaso@webrtc.org Extend IceControllerFactoryArgs with field trial string
2020-04-26 peah@webrtc.org APM: Add build flag to allow building WebRTC without APM
2020-04-25 mbonadei@webrtc.org Fix the name of the file generated by generate_sslroots.py.
2020-04-24 mbonadei@webrtc.org Update set of known root certificates.

Created with:
  gclient setdep -r src/third_party/webrtc@f7f7cc93aa44

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:1024965,chromium:978779
Tbr: webrtc-chromium-sheriffs-robots@google.com
Change-Id: Ib1f1594b9c051a8919ac7f57c384a168444f4ca2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2167781Reviewed-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@{#762779}

DEPS

@@ -1447,7 +1447,7 @@ deps = {
   },
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '1b8ef63876ebfa55a51c8ca9b1d8206bf8233e01',
+    Var('webrtc_git') + '/src.git' + '@' + 'f7f7cc93aa44a5a514e6a79771eabbc390103584',
 
   'src/third_party/libgifcodec':
      Var('skia_git') + '/libgifcodec' + '@'+  Var('libgifcodec_revision'),