Yeah, there's an unfortunate split between "action spawned in system tray" that ash knows about and "action spawned via chrome window widget" that the browser knows about.

That said, it's all uma, so it might be possible to just inline the calls in the right places. It's the shared enums that are the problem.

The enums are easily moved to public/cpp, but I had assumed logging from multiple processes would be problematic until bug 642762 was fixed.

Yeah, the logging won't actually work until that bug is fixed, but I don't think we have to wait on it. Ash already does a bunch of UMA logging today, so that bug has to be fixed before we can ship. I've moved a couple things into ash just because I know that's where they'll need to go eventually. As long as things still work in classic ash I think it's OK to do that sort of thing now.

UMA logging in ash works under mash (see bug 642762, I also manually tested), so I'm going to this now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c13bd479d3cc41391c8927c19134f2e592e6b198

commit c13bd479d3cc41391c8927c19134f2e592e6b198
Author: James Cook <jamescook@chromium.org>
Date: Tue May 01 17:15:08 2018

cros: Remove references to ash::MultiProfileUMA from chrome/browser

For out-of-process ash code in //chrome cannot call directly into
//ash. See //ash/README.md

* Deprecate MultiProfile.SessionMode since there is only one mode now
* Deprecate MultiProfile.TeleportWindow since it was not being
  maintained
* Migrate metrics only recorded by chrome into //chrome/browser
* Clean up some comments about MultiWindowUserManager

windows between accounts, verify MultiProfile.* counts in

Bug:  766407 
Test: unit_tests, manually sign in multiple users and teleport
chrome: //histograms
Change-Id: I3a5f21be9504268d91c66090512c42ac293b18ad
Reviewed-on: https://chromium-review.googlesource.com/1036200
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555085}
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/ash/multi_profile_uma.cc
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/ash/multi_profile_uma.h
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
[delete] https://crrev.com/c30400f1f0334084f186685447485b69350830f2/chrome/browser/chromeos/profiles/DEPS
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/chrome/browser/ui/ash/launcher/chrome_launcher_controller.cc
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/chrome/browser/ui/ash/multi_user/multi_user_context_menu_chromeos.cc
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/chrome/browser/ui/ash/multi_user/multi_user_window_manager.cc
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/chrome/browser/ui/ash/multi_user/multi_user_window_manager.h
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/c13bd479d3cc41391c8927c19134f2e592e6b198/tools/metrics/histograms/histograms.xml