Could you specify if these tests have always failed in mash, or started to fail because of the recent refactoring? Thanks! (During the refactoring we intentionally make mash fail under certain situations, and it will be fixed after the refactoring. But if these tests never intend to work in mash then it's a different issue.)

The tests started to fail with:

 https://chromium-review.googlesource.com/c/chromium/src/+/770711

presumably related to:
"MASH does not crash when setting wallpaper, but it won't be able
to save wallpaper. The wallpaper newly set during an active session
will be lost when the session ends."

There is no reason why we should expect them to fail once the re-factoring is completed, as far as I am aware.

Thanks! They will be fixed when the re-factoring is completed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e291d73a4a74f5693e37e53ce309e2729f7e50de

commit e291d73a4a74f5693e37e53ce309e2729f7e50de
Author: Steven Bennetts <stevenjb@chromium.org>
Date: Wed Dec 06 23:16:53 2017

Mash: Disable WallpapaerPrivateApiTest

Bug:  792641 
Change-Id: I6fe3df805cf2efcfded5c3633d07f4931314864c
Reviewed-on: https://chromium-review.googlesource.com/809931
Reviewed-by: Wenzhao (Colin) Zang <wzang@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522242}
[modify] https://crrev.com/e291d73a4a74f5693e37e53ce309e2729f7e50de/testing/buildbot/filters/mojo.fyi.mash.browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/906d147a6673ddad6694329d77db576a9630ef2e

commit 906d147a6673ddad6694329d77db576a9630ef2e
Author: Wenzhao Zang <wzang@chromium.org>
Date: Wed Feb 28 01:19:11 2018

Mash: Enable WallpapaerPrivateApiTest

The test passes after wallpaper refactoring is completed.

Bug:  792641 
Change-Id: I13939dcf69c3317b53d5338906bd277a2222aba3
Reviewed-on: https://chromium-review.googlesource.com/917436
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539617}
[modify] https://crrev.com/906d147a6673ddad6694329d77db576a9630ef2e/testing/buildbot/filters/mash.browser_tests.filter