Suspecting and reverting https://chromium-review.googlesource.com/c/chromium/src/+/1013957, which added the test.

I can't revert, due to non-trivial merge conflicts. I will disable the test instead.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/de283c36cd486f2414fbdec92debc8f93d8f695f

commit de283c36cd486f2414fbdec92debc8f93d8f695f
Author: Christos Froussios <cfroussios@chromium.org>
Date: Mon Apr 30 11:55:02 2018

Disable CrSettingsCrostiniPageTest.All on ChromeOS dbg

The test is failing and the offending CL cannot be trivially reverted.

TBR=rjwright@chromium.org

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  838097 
Change-Id: I1f32a74ab6693f0532c9edc2cbc0af554b2ae656
Reviewed-on: https://chromium-review.googlesource.com/1034684
Reviewed-by: Christos Froussios <cfroussios@chromium.org>
Commit-Queue: Christos Froussios <cfroussios@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554724}
[modify] https://crrev.com/de283c36cd486f2414fbdec92debc8f93d8f695f/chrome/test/data/webui/settings/cr_settings_browsertest.js

The builder is green now.

 Issue 838080  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/87fcd9a90813432bbfc727143b5c6810c48353a5

commit 87fcd9a90813432bbfc727143b5c6810c48353a5
Author: Renee Wright <rjwright@chromium.org>
Date: Tue May 08 05:31:53 2018

Remove dialog part of CrostiniPageTests & re-enable

This test was failing in debug.

  onRemoveTap_: function(event) {
    this.showRemoveDialog_ = true;
    this.async(() => this.$$('#removeDialog').showModal());
  },

in

cs.chromium.org/chromium/src/chrome/browser/resources/settings/crostini_page/crostini_subpage.js

always comes up with

this.$$('#removeDialog').showModal == undefined

in debug. I do not know why. But this dialog is being
replace with a View dialog very soon anyway.

Bug:  838097 
Change-Id: Id78b498ee9ce54849793eb9518bbb513a426f13d
Reviewed-on: https://chromium-review.googlesource.com/1036710
Commit-Queue: Renée Wright <rjwright@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556698}
[modify] https://crrev.com/87fcd9a90813432bbfc727143b5c6810c48353a5/chrome/test/data/webui/settings/cr_settings_browsertest.js
[modify] https://crrev.com/87fcd9a90813432bbfc727143b5c6810c48353a5/chrome/test/data/webui/settings/crostini_page_test.js