Roll src/third_party/webrtc 3d351c688586..8d4105850c66 (2 commits)

https://webrtc.googlesource.com/src.git/+log/3d351c688586..8d4105850c66

git log 3d351c688586..8d4105850c66 --date=short --no-merges --format='%ad %ae %s'
2019-08-05 mbonadei@webrtc.org Remove unused rtc_tools/video_analysis.py.
2019-08-05 chxg@google.com Remove the old `ContributingSources` class.

Created with:
  gclient setdep -r src/third_party/webrtc@8d4105850c66

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.


TBR=webrtc-chromium-sheriffs-robots@google.com

Bug: chromium:None
Change-Id: Ibff74229a41e0eb63e42387ca5377f36270831c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1736799
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@{#684012}