Roll src/third_party/webrtc 77894ccb5df0..a713505c1888 (4 commits)

https://webrtc.googlesource.com/src.git/+log/77894ccb5df0..a713505c1888


git log 77894ccb5df0..a713505c1888 --date=short --no-merges --format='%ad %ae %s'
2018-12-04 terelius@webrtc.org Preserve timestamp in DTLS writable event.
2018-12-04 danilchap@webrtc.org Revert "Change ReceiveStatistics reaction to large sequence numbers jumps"
2018-12-04 zstein@webrtc.org Offset IceCandidatePairEventType enum in event log visualizer
2018-12-04 ilnik@webrtc.org Vp9 flexible mode fixes


Created with:
  gclient setdep -r src/third_party/webrtc@a713505c1888

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

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;luci.chromium.try:mac_chromium_archive_rel_ng

BUG=chromium:b/38179459,chromium:NONE
TBR=webrtc-chromium-sheriffs-robots@google.com

Change-Id: I2771f8eb9441f892d604e22a69f5c5ba9b7dde5d
Reviewed-on: https://chromium-review.googlesource.com/c/1362285
Reviewed-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@{#613865}

DEPS

@@ -1171,7 +1171,7 @@ deps = {
     Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + '5b6cbd789b9b91b4e46dde883c9f2ecb31eddade',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '77894ccb5df02e810e7a1a80c1b2c4df82cac46f',
+    Var('webrtc_git') + '/src.git' + '@' + 'a713505c1888b86684054656e3d8801c8057c8d4',
 
   'src/third_party/xdg-utils': {
       'url': Var('chromium_git') + '/chromium/deps/xdg-utils.git' + '@' + 'd80274d5869b17b8c9067a1022e4416ee7ed5e0d',