javierrobles@ is the sheriff, but he is in EMEA timezone.
One option is to revert one of his recent CLs, may be one of these:
  https://chromium-review.googlesource.com/c/chromium/src/+/1172289
  https://chromium-review.googlesource.com/c/chromium/src/+/1172287
  https://chromium-review.googlesource.com/c/chromium/src/+/1131511

This is the first failing build:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/ios-uirefresh-simulator/1565

crrev.com/c/1172287 is in the build, so let me speculatively revert it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/87eea47252306894df77c66040d7cce248e2ecbb

commit 87eea47252306894df77c66040d7cce248e2ecbb
Author: Makoto Shimazu <shimazu@chromium.org>
Date: Tue Aug 14 03:49:51 2018

Revert "[iOS] ActivityService cleanup"

This reverts commit 76c127f698ed6c6bf0eaa09b8b738acf4552c119.

Reason for revert: This needs to be reverted first to revert crrev.com/c/1172287.

Original change's description:
> [iOS] ActivityService cleanup
>
> Cleanup for the ActivityService.
>
> Bug: none
> Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
> Change-Id: I7feb4acc2711172dfb9829c2b223e6f2c724fa33
> Reviewed-on: https://chromium-review.googlesource.com/1172289
> Commit-Queue: Gauthier Ambard <gambard@chromium.org>
> Reviewed-by: Peter Lee <pkl@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#582599}

TBR=pkl@chromium.org,gambard@chromium.org

Change-Id: I1a2b122518b7b845274a4d27bc897eb9d195a2dd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  873718 
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Reviewed-on: https://chromium-review.googlesource.com/1173891
Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582825}
[modify] https://crrev.com/87eea47252306894df77c66040d7cce248e2ecbb/ios/chrome/browser/ui/activity_services/share_to_data.h
[modify] https://crrev.com/87eea47252306894df77c66040d7cce248e2ecbb/ios/chrome/browser/ui/activity_services/share_to_data.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f

commit 036d3ed6c39ab09d0dcbe25829ddd8827f053a1f
Author: Makoto Shimazu <shimazu@chromium.org>
Date: Tue Aug 14 03:51:11 2018

Revert "Show FindInPage activity only when it is relevant"

This reverts commit cdcdc5ea86db7374d153e8436e388dfbc5fc709b.

Reason for revert: ios_chrome_unittests fails.


Original change's description:
> Show FindInPage activity only when it is relevant
> 
> The FindInPage activity should only be shown when the FindInPage action
> is doing something.
> This CL adds a BOOL to know if the page can be searched. It is used to
> display the activity or not.
> 
> Bug:  871260 
> Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
> Change-Id: I514b67e4b7e0f00258c0c1a8310975394ac3468c
> Reviewed-on: https://chromium-review.googlesource.com/1172287
> Commit-Queue: Gauthier Ambard <gambard@chromium.org>
> Reviewed-by: Peter Lee <pkl@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#582590}

TBR=pkl@chromium.org,gambard@chromium.org

Change-Id: Ibc4e514b67ef554a4b0fe49841499b10d638c3c2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  871260 ,  873718 
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Reviewed-on: https://chromium-review.googlesource.com/1173871
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582826}
[modify] https://crrev.com/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f/ios/chrome/browser/ui/activity_services/BUILD.gn
[modify] https://crrev.com/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f/ios/chrome/browser/ui/activity_services/activity_service_controller.mm
[modify] https://crrev.com/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f/ios/chrome/browser/ui/activity_services/activity_service_controller_unittest.mm
[modify] https://crrev.com/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f/ios/chrome/browser/ui/activity_services/share_to_data.h
[modify] https://crrev.com/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f/ios/chrome/browser/ui/activity_services/share_to_data.mm
[modify] https://crrev.com/036d3ed6c39ab09d0dcbe25829ddd8827f053a1f/ios/chrome/browser/ui/activity_services/share_to_data_builder.mm

Tests aren't failing anymore, the CL will be fixed then relanded.