Roll src/third_party/webrtc c782263e5f19..b2678cfefedd (4 commits)

https://webrtc.googlesource.com/src.git/+log/c782263e5f19..b2678cfefedd

git log c782263e5f19..b2678cfefedd --date=short --first-parent --format='%ad %ae %s'
2020-03-10 chromium-webrtc-autoroll@webrtc-ci.iam.gserviceaccount.com Roll chromium_revision 5a78076c..29afd4ae (748288:748637)
2020-03-10 srte@webrtc.org Cleanup: Removes unused AimdRateControl field trials.
2020-03-10 ilnik@webrtc.org Reland "Wire up internal libvpx VP9 scaler to statistics proxy"
2020-03-10 phoglund@webrtc.org Hand protos directly to histograms and fix summary.

Created with:
  gclient setdep -r src/third_party/webrtc@b2678cfefedd

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:1029452
Tbr: webrtc-chromium-sheriffs-robots@google.com
Change-Id: I611e65e64cfce1d9db1be6d96fce09e86c0dbe06
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2096090Reviewed-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@{#748719}

DEPS

@@ -1454,7 +1454,7 @@ deps = {
     Var('chromium_git') + '/external/github.com/gpuweb/cts.git' + '@' + 'ec18cc3262922e7dcdbe70243c6f40606f979144',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + 'c782263e5f19f7c30d0b2120a8ec2383111ac1c6',
+    Var('webrtc_git') + '/src.git' + '@' + 'b2678cfefeddc9291863f560f417b64949eac8ac',
 
   'src/third_party/libgifcodec':
      Var('skia_git') + '/libgifcodec' + '@'+  Var('libgifcodec_revision'),