It started flaking ( Issue 877129 ). After a fix in r586185, the failures seem reliable now. But restricted to Windows 10 for some reason.

disable cl -> https://chromium-review.googlesource.com/c/chromium/src/+/1189267

[ RUN      ] AppWindowApiTest.Get
[2880:7412:0826/213920.819:WARNING:discovery_network_list_win.cc(195)] Failed to open Wlan client handle: 1062
[2880:4948:0826/213920.830:WARNING:chrome_browser_main_win.cc(641)] Command line too long for RegisterApplicationRestart:  --brave-new-test-launcher --cfi-diag=0 --disable-gpu-process-for-dx12-vulkan-info-collection --gtest_also_run_disabled_tests --gtest_filter=AppWindowApiTest.Get --single_process --test-launcher-bot-mode --test-launcher-output="C:\b\s\w\itmru76a\scoped_dir6368_8901\results6368_10438\test_results.xml" --test-launcher-summary-output="C:\b\s\w\ioql8ajh\output.json" --user-data-dir="C:\b\s\w\itmru76a\scoped_dir6368_8901\d6368_29684" --disable-offline-auto-reload --no-first-run --no-default-browser-check --enable-logging=stderr --disable-default-apps --wm-window-animations-disabled --disable-component-update --test-type=browser --force-color-profile=srgb --disable-zero-browsers-open-for-tests --ipc-connection-timeout=30 --allow-file-access-from-files --dom-automation --log-gpu-control-list-decisions --disable-backgrounding-occluded-windows --disable-gl-drawing-for-tests --override-use-software-gl-for-tests --force-color-profile=srgb --disable-compositor-ukm-for-tests --enable-features=TestFeatureForBrowserTest1 --disable-features=NetworkPrediction,SpeculativePreconnect,TestFeatureForBrowserTest2,WebRTC-H264WithOpenH264FFmpeg --disable-gpu-process-for-dx12-vulkan-info-collection --flag-switches-begin --flag-switches-end --file-url-path-alias="/gen=C:\b\s\w\ir\out\Release_x64\gen" --restore-last-session about:blank
[2880:4948:0826/213923.104:INFO:CONSOLE(0)] "[SUCCESS] testGetAllNoWindows", source: chrome-extension://jnmonidcdjeiakmbafnejcclknocbpen/_generated_background_page.html (0)
[2880:4948:0826/213923.169:INFO:CONSOLE(0)] "[SUCCESS] testGetAllOneWindow", source: chrome-extension://jnmonidcdjeiakmbafnejcclknocbpen/_generated_background_page.html (0)
[2880:4948:0826/213923.253:INFO:CONSOLE(0)] "[FAIL] testGetAllMultipleWindows: API Test Error in testGetAllMultipleWindows
Actual: win2
Expected: win1
Error
    at extensions::test:243:18
    at chrome-extension://jnmonidcdjeiakmbafnejcclknocbpen/background.js:35:27", source: chrome-extension://jnmonidcdjeiakmbafnejcclknocbpen/_generated_background_page.html (0)
[2880:4948:0826/213923.253:INFO:CONSOLE(138)] "Uncaught chrome.test.failure", source: extensions::test (138)
[2880:4948:0826/213923.255:INFO:CONSOLE(0)] "[SUCCESS] testGetNoWindows", source: chrome-extension://jnmonidcdjeiakmbafnejcclknocbpen/_generated_background_page.html (0)

attempt #2 --> https://chromium-review.googlesource.com/c/chromium/src/+/1188736

https://chromium-review.googlesource.com/c/chromium/src/+/1188736

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d9a9af50f975f4cc520c05df41353ac5cbc03397

commit d9a9af50f975f4cc520c05df41353ac5cbc03397
Author: Trent Apted <tapted@chromium.org>
Date: Mon Aug 27 07:34:43 2018

Fix AppWindowApiTest.Get#testGetAllMultipleWindows properly

Its comparator was rubbish and always has been. Array.prototype.sort()
takes a function that should return {-1, 0, 1}, not bool.

TBR=benwells@chromium.org

Bug:  877890 
Change-Id: I65162d2b261ad4ff91a028bf62c0cdcfb765df27
Reviewed-on: https://chromium-review.googlesource.com/1188736
Reviewed-by: Trent Apted <tapted@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586206}
[modify] https://crrev.com/d9a9af50f975f4cc520c05df41353ac5cbc03397/chrome/test/data/extensions/platform_apps/windows_api_get/background.js