Steven, is there anyone on the CrOS side that could help with some of these tests?

Not really :( I've been asking for more CrOS Settings developers for months now.

In case anyone has spare cycles, the updated list of failing tests can be found at https://cs.chromium.org/chromium/src/testing/buildbot/filters/webui_polymer2_browser_tests.filter?l=39.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/06197f92d96eb98ff7aca94255c18f649a1f5e36

commit 06197f92d96eb98ff7aca94255c18f649a1f5e36
Author: rbpotter <rbpotter@chromium.org>
Date: Wed Oct 03 21:32:40 2018

Settings WebUI: Enable various already passing tests in Polymer2.

Enabling:
CrSettingsIncompatibleApplicationsPageTest
CrSettingsLanguagesPageTest.AddLanguagesDialog
CrSettingsLanguagesPageTest.LanguageMenu
CrSettingsLanguagesPageTest.Spellcheck

Bug:  875452 ,  875454 
Change-Id: I5b5fa399bb76ec133e2cfee1ae3b949eedb7c7db
Reviewed-on: https://chromium-review.googlesource.com/c/1259465
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596376}
[modify] https://crrev.com/06197f92d96eb98ff7aca94255c18f649a1f5e36/testing/buildbot/filters/webui_polymer2_browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d

commit 782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d
Author: rbpotter <rbpotter@chromium.org>
Date: Thu Oct 04 18:02:56 2018

Settings UI: Fix and re-enable device page tests with Polymer2

Re-enabling the following already passing tests:
CrSettingsDevicePageTest.KeyboardTest
CrSettingsDevicePageTest.PointersTest

Fixing and re-enabling the following failing tests:
CrSettingsDevicePageTest.DisplayTest
CrSettingsDevicePageTest.PowerTest

Bug:  875454 
Change-Id: Ie641b828b4076e9aaed6e0faf2adcd7b9bce3477
Reviewed-on: https://chromium-review.googlesource.com/c/1260497
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596755}
[modify] https://crrev.com/782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d/chrome/browser/resources/settings/device_page/display.js
[modify] https://crrev.com/782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d/chrome/browser/resources/settings/device_page/display_layout.js
[modify] https://crrev.com/782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d/chrome/browser/resources/settings/device_page/layout_behavior.js
[modify] https://crrev.com/782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d/chrome/browser/resources/settings/device_page/power.js
[modify] https://crrev.com/782ba9acb7f459ed4f0453f6e0ccdfd83aa7e70d/testing/buildbot/filters/webui_polymer2_browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3ac9efde13ee571387899d6d3fcf12e3d543e963

commit 3ac9efde13ee571387899d6d3fcf12e3d543e963
Author: rbpotter <rbpotter@chromium.org>
Date: Fri Oct 05 15:07:40 2018

Settings UI: Fix and re-enable AddLanguagesDialog test

This test was flaky when run with Polymer 2, specifically failing to
find > 0 non-hidden list items in the dialog. This appears to have been
due to a timing issue with the setTimeout() call in the test setup
causing the test to fail inconsistently. This failure could not be
reproduced locally with the original test. However, exchanging
setTimeout() for waiting for the dialog to open resulted in the same
failure occurring consistently with Polymer 2 (but not with Polymer 1).
The failure was then fixed by adding Polymer.dom.flush() to ensure the
dialog had finished filtering languages before querying for the items.

Bug:  875454 ,  891955 
Change-Id: I05c2b60ad0d12619e388a5469a0c1a0418e35a8c
Reviewed-on: https://chromium-review.googlesource.com/c/1262973
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597124}
[modify] https://crrev.com/3ac9efde13ee571387899d6d3fcf12e3d543e963/chrome/test/data/webui/settings/cr_settings_browsertest.js
[modify] https://crrev.com/3ac9efde13ee571387899d6d3fcf12e3d543e963/chrome/test/data/webui/settings/languages_page_tests.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9f287737152fd0d7adcb6f67ebef670e77ad93bb

commit 9f287737152fd0d7adcb6f67ebef670e77ad93bb
Author: rbpotter <rbpotter@chromium.org>
Date: Fri Oct 05 19:01:49 2018

Settings UI: Fix internet page tests to work with Polymer2

Fixing and enabling:
CrSettingsInternetDetailPageTest.InternetDetailPage
CrSettingsInternetPageTest.InternetPage

Bug:  875454 
Change-Id: I2a1f31c623d67e178ab99d3558aa9e7e06a8c8c0
Reviewed-on: https://chromium-review.googlesource.com/c/1262934
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597223}
[modify] https://crrev.com/9f287737152fd0d7adcb6f67ebef670e77ad93bb/chrome/browser/resources/settings/internet_page/internet_detail_page.js
[modify] https://crrev.com/9f287737152fd0d7adcb6f67ebef670e77ad93bb/chrome/browser/resources/settings/internet_page/internet_subpage.js
[modify] https://crrev.com/9f287737152fd0d7adcb6f67ebef670e77ad93bb/chrome/test/data/webui/settings/internet_page_tests.js
[modify] https://crrev.com/9f287737152fd0d7adcb6f67ebef670e77ad93bb/testing/buildbot/filters/webui_polymer2_browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/54f66a499b3e122639234a6850d0db47cca2f2be

commit 54f66a499b3e122639234a6850d0db47cca2f2be
Author: rbpotter <rbpotter@chromium.org>
Date: Sat Oct 06 00:05:14 2018

Settings UI: Fix and re-enable some tests with Polymer 2

Re-enabling:
CrSettingsCrostiniPageTest.All
since it now seems to be passing on ToT.

Fixing and re-enabling:
CrSettingsBluetoothPageTest.All

Bug:  875454 
Change-Id: I0a4211439267d5e9efc9a4cb6a04e6964ba0e7fd
Reviewed-on: https://chromium-review.googlesource.com/c/1265824
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597375}
[modify] https://crrev.com/54f66a499b3e122639234a6850d0db47cca2f2be/chrome/test/data/webui/settings/fake_bluetooth_private.js
[modify] https://crrev.com/54f66a499b3e122639234a6850d0db47cca2f2be/testing/buildbot/filters/webui_polymer2_browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4efd01f508b64532a9d87a4027e34917f69f5bbd

commit 4efd01f508b64532a9d87a4027e34917f69f5bbd
Author: rbpotter <rbpotter@chromium.org>
Date: Mon Oct 08 22:20:21 2018

Settings UI: Fix Multidevice page tests to work with Polymer 2

Fixing and enabling:
CrSettingsMultidevicePageTest.All
CrSettingsMultideviceSubpageTest.All

Bug:  875454 
Change-Id: I8e8e629c6860ddc1ba261490f585c92f41280fe3
Reviewed-on: https://chromium-review.googlesource.com/c/1265016
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597703}
[modify] https://crrev.com/4efd01f508b64532a9d87a4027e34917f69f5bbd/chrome/browser/resources/settings/internet_page/network_summary_item.js
[modify] https://crrev.com/4efd01f508b64532a9d87a4027e34917f69f5bbd/chrome/test/data/webui/settings/multidevice_page_tests.js
[modify] https://crrev.com/4efd01f508b64532a9d87a4027e34917f69f5bbd/testing/buildbot/filters/webui_polymer2_browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f63468bdb3708e99ba83d45856c6f958fbb55eeb

commit f63468bdb3708e99ba83d45856c6f958fbb55eeb
Author: rbpotter <rbpotter@chromium.org>
Date: Wed Oct 10 02:20:27 2018

Settings UI: Fix some PeoplePage tests to work with Polymer2

Fixing and enabling:
CrSettingsPeoplePageLockScreenTest.All
CrSettingsPeoplePageQuickUnlockAuthenticateTest.All

Bug:  875454 
Change-Id: Ic58f759b381ca1d47c4e8f4106f3b507e002a912
Reviewed-on: https://chromium-review.googlesource.com/c/1271585
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598181}
[modify] https://crrev.com/f63468bdb3708e99ba83d45856c6f958fbb55eeb/chrome/test/data/webui/settings/cr_settings_browsertest.js
[modify] https://crrev.com/f63468bdb3708e99ba83d45856c6f958fbb55eeb/chrome/test/data/webui/settings/quick_unlock_authenticate_browsertest_chromeos.js
[modify] https://crrev.com/f63468bdb3708e99ba83d45856c6f958fbb55eeb/testing/buildbot/filters/webui_polymer2_browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fcb5be8f285963a1aca816d8764e03e9cd1624b3

commit fcb5be8f285963a1aca816d8764e03e9cd1624b3
Author: rbpotter <rbpotter@chromium.org>
Date: Fri Oct 12 01:08:59 2018

Settings UI: Fix PeoplePageSetupPinDialogTest to work with Polymer2

Fixing CrSettingsPeoplePageSetupPinDialogTest.All with 2 changes:
(1) Reading updated pin dialog from the pin-change event, rather than
    from |pinKeyboardValue_|. In Polymer 2, this value is not updated
    at the time the pin-change event arrives.
(1) In the test for the backspace button, set the value in cr-input
    instead of on the pinKeyboard directly, so that |selectionStart_|,
    used to determine if the backspace key should be enabled, will be
    > 0.

Bug:  875454 
Change-Id: Iec83f3a85a4d04fe710cb6b5e23b99d59be54f49
Reviewed-on: https://chromium-review.googlesource.com/c/1274462
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599053}
[modify] https://crrev.com/fcb5be8f285963a1aca816d8764e03e9cd1624b3/chrome/test/data/webui/settings/quick_unlock_authenticate_browsertest_chromeos.js
[modify] https://crrev.com/fcb5be8f285963a1aca816d8764e03e9cd1624b3/testing/buildbot/filters/webui_polymer2_browser_tests.filter
[modify] https://crrev.com/fcb5be8f285963a1aca816d8764e03e9cd1624b3/ui/webui/resources/cr_components/chromeos/quick_unlock/setup_pin_keyboard.js