These tests are failing:

ProfileChooserViewExtensionsTest.InvokeUi_Guest
ProfileChooserViewExtensionsTest.InvokeUi_MultiProfile
ProfileChooserViewExtensionsTest.LockProfileBlockExtensions
ProfileChooserViewExtensionsTest.LockProfile
ProfileChooserViewExtensionsTest.InvokeUi_SupervisedOwner
ProfileChooserViewExtensionsTest.InvokeUi_SupervisedUser
ProfileChooserViewExtensionsTest.LockProfileNoBlockOtherProfileExtensions

logs contain this which seems relevant:

ERROR:browser_dm_token_storage_linux.cc(93)] Error: /etc/machine-id contains 0 characters (32 were expected).
ERROR:bus.cc(394)] Failed to connect to the bus: Could not parse server address: Unknown address type (examples of valid types are "tcp" and on UNIX "unix")
WARNING:password_store_factory.cc(261)] Using basic (unencrypted) store for password storage. See https://chromium.googlesource.com/chromium/src/+/master/docs/linux_password_storage.md for more information about password storage options.
(browser_tests:11129): LIBDBUSMENU-GLIB-WARNING **: Unable to get session bus: Unknown or unsupported transport 'disabled' for address 'disabled:'
WARNING:password_store_factory.cc(261)] Using basic (unencrypted) store for password storage. See https://chromium.googlesource.com/chromium/src/+/master/docs/linux_password_storage.md for more information about password storage options.
==11129==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x14f82cc1 in profiles::GetProfileSwitcherTextForItem(AvatarMenu::Item const&) ./../../chrome/browser/profiles/profiles_state.cc:125:7


ultrotter@: PTAL.  i'm assigning to you because you've made some changes that affect profiles (https://chromium-review.googlesource.com/1233577 in the blame list).  it's unclear to me that this is directly related, but you also seem to be much more knowledgeable about this part of chrome than I am.

please re-assign if necessary.

thanks!

Fixed by https://chromium-review.googlesource.com/c/chromium/src/+/1238113.