Roll src/third_party/webrtc 81f51975125c..42f0d78f1ee8 (3 commits)

https://webrtc.googlesource.com/src.git/+log/81f51975125c..42f0d78f1ee8


git log 81f51975125c..42f0d78f1ee8 --date=short --no-merges --format='%ad %ae %s'
2018-06-27 titovartem@webrtc.org Roll back checking in the third_party directory
2018-06-27 mhoro@webrtc.org Revert two instances of num_active_spatial_layers.
2018-06-27 alexnarest@webrtc.org Allows audio bitrate allocation in video calls without enabling TWCC (Transport Wide Congestion Control as defined at https://tools.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01.html) for audio stream.


Created with:
  gclient setdep -r src/third_party/webrtc@42f0d78f1ee8

The AutoRoll server is located here: https://webrtc-chromium-roll.skia.org

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux_chromium_archive_rel_ng;master.tryserver.chromium.mac:mac_chromium_archive_rel_ng

BUG=chromium:None
TBR=webrtc-chromium-sheriffs-robots@google.com

Change-Id: Icdc652eb9deb1f121940060d7f912dc8bf492587
Reviewed-on: https://chromium-review.googlesource.com/1117139Reviewed-by: webrtc-chromium-autoroll <webrtc-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: webrtc-chromium-autoroll <webrtc-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#570854}

DEPS

@@ -1032,7 +1032,7 @@ deps = {
     Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + '5e83981c2c44f24109b96b555d6865d481e0c609',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '81f51975125c6c12b6dc9fd470132c78ef4812c9',
+    Var('webrtc_git') + '/src.git' + '@' + '42f0d78f1ee830ba6f62bc3c6364dba121144681',
 
   'src/third_party/xdg-utils': {
       'url': Var('chromium_git') + '/chromium/deps/xdg-utils.git' + '@' + 'd80274d5869b17b8c9067a1022e4416ee7ed5e0d',