Roll src/third_party/webrtc 6620506591b7..13ea34f30537 (2 commits)

https://webrtc.googlesource.com/src.git/+log/6620506591b7..13ea34f30537

git log 6620506591b7..13ea34f30537 --date=short --first-parent --format='%ad %ae %s'
2019-11-25 steveanton@webrtc.org Revert "Add IvfVideoFrameGenerator"
2019-11-25 elrello@microsoft.com Address failing wpt test cases for the rollback feature

Created with:
  gclient setdep -r src/third_party/webrtc@13ea34f30537

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/+/master/autoroll/README.md

Bug: chromium:1025557,chromium:1025542
Tbr: webrtc-chromium-sheriffs-robots@google.com
Change-Id: I8c25c235083e26df7cc59d4746006311e4c3658e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1935436Reviewed-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@{#718951}

DEPS

@@ -1494,7 +1494,7 @@ deps = {
     Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + 'dd55f3ca8f2ea716ca917a4aaf36f0729fe902b1',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + '6620506591b7910e50188da6b9bd7cdf6f9c3c04',
+    Var('webrtc_git') + '/src.git' + '@' + '13ea34f30537000ae60bcb7cdcd6dce72b64134b',
 
   # Wuffs' canonical repository is at github.com/google/wuffs, but we use
   # Skia's mirror of Wuffs, the same as in upstream Skia's DEPS file.