Roll src/third_party/webrtc/ a7678667f..1b8205f9e (3 commits)

https://webrtc.googlesource.com/src.git/+log/a7678667fc72..1b8205f9ee8f

$ git log a7678667f..1b8205f9e --date=short --no-merges --format='%ad %ae %s'

Created with:
  roll-dep src/third_party/webrtc
BUG=None,None,None


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

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls


CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_archive_rel_ng;master.tryserver.chromium.mac:mac_chromium_archive_rel_ng
TBR=webrtc-chromium-sheriffs-robots@google.com

Change-Id: I449961bbb03939a6f50944586cbcb06498bda06b
Reviewed-on: https://chromium-review.googlesource.com/745904Reviewed-by: WebRTC Roll Bot <webrtc-autoroll@chromium.org>
Commit-Queue: WebRTC Roll Bot <webrtc-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512807}

DEPS

@@ -605,7 +605,7 @@ deps = {
     Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + '34842fa3c36988840c89f5bc6a68503175acf7d9',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + 'a7678667fc726979ca27d2429689d5735cca425d', # commit position 20237
+    Var('webrtc_git') + '/src.git' + '@' + '1b8205f9ee8fda98ddb66c464c7e4d8bfa49cf50', # commit position 20237
 
   'src/third_party/xdg-utils': {
       'url': Var('chromium_git') + '/chromium/deps/xdg-utils.git' + '@' + 'd80274d5869b17b8c9067a1022e4416ee7ed5e0d',