Not sure who this would go to. 

FYI - a short link to file infra bugs for ios is http://go/ios-ops-ticket .

The failures are in isolated tests that are run on separate swarming bots. The first failing test from that failing build: https://chromium-swarm.appspot.com/task?id=40153111b76ba310 shows that it tries to install Xcode 10 on Mac 10.12.6. The minimum required version is 10.13.4; so your build configs need to be adjusted to request appropriate Mac OS versions, similar to e.g. https://cs.chromium.org/chromium/src/ios/build/bots/chromium.mac/ios-simulator.json?l=27&rcl=d157b3968431272cf98ef6b030886c938bcd1047

I'll take this as the current trooper, will see if I can find and update your configs.

CL: https://webrtc-review.googlesource.com/c/src/+/101944 .

The following revision refers to this bug:
  https://webrtc.googlesource.com/src.git/+/d5bc865f136cc03d5c11ba8447728995f925cf69

commit d5bc865f136cc03d5c11ba8447728995f925cf69
Author: Sergey Berezin <sergeyberezin@chromium.org>
Date: Wed Sep 26 09:50:35 2018

[ios] Update swarming dimensions for Xcode 10

Bug:  chromium:888513 
Change-Id: I55fb5522cc4beee8e657d63bd2a166bce8b7291e
Reviewed-on: https://webrtc-review.googlesource.com/101944
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24844}
[modify] https://crrev.com/d5bc865f136cc03d5c11ba8447728995f925cf69/tools_webrtc/ios/client.webrtc/iOS32_Sim_Debug_(iOS_9.0).json
[modify] https://crrev.com/d5bc865f136cc03d5c11ba8447728995f925cf69/tools_webrtc/ios/client.webrtc/iOS64_Sim_Debug_(iOS_11.0).json
[modify] https://crrev.com/d5bc865f136cc03d5c11ba8447728995f925cf69/tools_webrtc/ios/client.webrtc/iOS64_Sim_Debug_(iOS_9.0).json

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/142e86c48db73f055e3e4d1806fdc62a4ec2d6b2

commit 142e86c48db73f055e3e4d1806fdc62a4ec2d6b2
Author: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Date: Wed Sep 26 13:33:02 2018

Roll src/third_party/webrtc 6f68324adbf5..569397fec738 (6 commits)

https://webrtc.googlesource.com/src.git/+log/6f68324adbf5..569397fec738


git log 6f68324adbf5..569397fec738 --date=short --no-merges --format='%ad %ae %s'
2018-09-26 philipel@webrtc.org Reland "Added field trial WebRTC-GenericDescriptor for the new generic descriptor."
2018-09-26 sergeyberezin@chromium.org [ios] Update swarming dimensions for Xcode 10
2018-09-26 kron@webrtc.org Reland "Second reland of "Optimize execution time of RTPSender::UpdateDelayStatistics""
2018-09-26 srte@webrtc.org Adds srte to OWNERS in bitrate_controller and remote_bitrate_estimator.
2018-09-26 buildbot@webrtc.org Roll chromium_revision c85bccf2fc..df010d520f (594059:594163)
2018-09-25 buildbot@webrtc.org Roll chromium_revision 5198eaca71..c85bccf2fc (593926:594059)


Created with:
  gclient setdep -r src/third_party/webrtc@569397fec738

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.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux_chromium_archive_rel_ng;luci.chromium.try:mac_chromium_archive_rel_ng

BUG= chromium:888513 ,chromium:None,chromium:None
TBR=webrtc-chromium-sheriffs-robots@google.com

Change-Id: Ib1a5803dbb0314adc76ac6cbfe56cc1d304658d4
Reviewed-on: https://chromium-review.googlesource.com/1245801
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@{#594299}
[modify] https://crrev.com/142e86c48db73f055e3e4d1806fdc62a4ec2d6b2/DEPS

Builds from https://ci.chromium.org/p/webrtc/builders/luci.webrtc.ci/iOS32%20Sim%20Debug%20%28iOS%209.0%29/7179 and onwards are green.