Roll WebRTC from 6e7167456b5e to c40073b687da (3 revisions)

https://webrtc.googlesource.com/src.git/+log/6e7167456b5e..c40073b687da

2020-12-03 philipp.hancke@googlemail.com doc: chrome://media-internals is useful for camera issues
2020-12-03 chromium-webrtc-autoroll@webrtc-ci.iam.gserviceaccount.com Roll chromium_revision a3682304..20fa2e0b (833048:833170)
2020-12-03 chromium-webrtc-autoroll@webrtc-ci.iam.gserviceaccount.com Roll chromium_revision 6b50907e..a3682304 (832826:833048)

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/+doc/master/autoroll/README.md

Bug: None
Tbr: webrtc-chromium-sheriffs-robots@google.com
Change-Id: I293b4fabc5086dd8ebe0b40578f3a567ad453606
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570402Reviewed-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@{#833250}

DEPS

@@ -1554,7 +1554,7 @@ deps = {
   },
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '6e7167456b5eba36c7985d6a74f1d191958d4e0f',
+    Var('webrtc_git') + '/src.git' + '@' + 'c40073b687dad9c505f5a012bb1014f7f39d816b',
 
   'src/third_party/libgifcodec':
      Var('skia_git') + '/libgifcodec' + '@'+  Var('libgifcodec_revision'),