Roll src/third_party/webrtc b4a6128e28a3..16946e3781ec (2 commits)

https://webrtc.googlesource.com/src.git/+log/b4a6128e28a3..16946e3781ec

git log b4a6128e28a3..16946e3781ec --date=short --no-merges --format='%ad %ae %s'
2019-08-29 sprang@webrtc.org Remove unused StorageType enum
2019-08-29 jakobi@webrtc.org Remove minimum bucket returned by histogram quantile function.

Created with:
  gclient setdep -r src/third_party/webrtc@16946e3781ec

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

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

Bug: None
Change-Id: If7dc4995bf95687d462f48cd5f50e45e9dcd8a9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1776199Reviewed-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@{#691629}

DEPS

@@ -1414,7 +1414,7 @@ deps = {
     Var('chromium_git') + '/external/khronosgroup/webgl.git' + '@' + 'abaae129d9a0c6e1e092067e0b105475df43352e',
 
   'src/third_party/webrtc':
-    Var('webrtc_git') + '/src.git' + '@' + 'b4a6128e28a371374a6ff703e83b1d0434769060',
+    Var('webrtc_git') + '/src.git' + '@' + '16946e3781ec30d23071b7c4a1484942642b46a4',
 
   'src/third_party/xdg-utils': {
       'url': Var('chromium_git') + '/chromium/deps/xdg-utils.git' + '@' + 'd80274d5869b17b8c9067a1022e4416ee7ed5e0d',