The profile error dialog runs a nested message loop. It seems to me that mojo messages are not delivered when there is a nested message loop. As a result, ACTIVE session state is not delivered to ash. Hence the wallpaper is not moved.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2404367d4408db72ffdda3a5d7e520ce9c4f4590

commit 2404367d4408db72ffdda3a5d7e520ce9c4f4590
Author: xiyuan <xiyuan@chromium.org>
Date: Wed Jun 14 15:17:29 2017

Make profile error dialog async

So that it does not run a nested message loop to block mojo
messages.

BUG= 729701 

Review-Url: https://codereview.chromium.org/2929953002
Cr-Commit-Position: refs/heads/master@{#479389}

[modify] https://crrev.com/2404367d4408db72ffdda3a5d7e520ce9c4f4590/chrome/browser/ui/android/simple_message_box_android.cc
[modify] https://crrev.com/2404367d4408db72ffdda3a5d7e520ce9c4f4590/chrome/browser/ui/cocoa/simple_message_box_mac.mm
[modify] https://crrev.com/2404367d4408db72ffdda3a5d7e520ce9c4f4590/chrome/browser/ui/profile_error_dialog.cc
[modify] https://crrev.com/2404367d4408db72ffdda3a5d7e520ce9c4f4590/chrome/browser/ui/simple_message_box.h
[modify] https://crrev.com/2404367d4408db72ffdda3a5d7e520ce9c4f4590/chrome/browser/ui/views/simple_message_box_views.cc

This bug requires manual review: M60 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(Desktop)

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Merged to branch 3112 in https://codereview.chromium.org/2951503002/