I could reproduce this on 68.0.3422.0/10653.0 on caroline.
However the Settings app launches correctly when it's launched by the "recently used apps" row.
So I think this is more likely related to the launcher, or Settings app.

+wutao

Hi xiyuan@, we open the Settings by this line of code [1]. Is the `profile' available for Guest? But it is hard to explain why "However the Settings app launches correctly when it's launched by the "recently used apps" row."

[1] https://cs.chromium.org/chromium/src/chrome/browser/ui/app_list/internal_app/internal_app_metadata.cc?l=64&rcl=d7e9702df54d7b686878eefaf1ec60647d425987

Looks like it is because the app in grid (created by InternalAppModelBuilder) uses the profile of AppListSycnableService, which always uses the original profile [1]. The one in recent app list (created by AppSearchProvider) uses the guest profile. And the original profile is not allowed in guest session so we hit this check [2].

Not sure what is the proper fix though. We do want to use the original profile for AppListSyncableService for regular users. Maybe add a guest session check to not redirect in such case.

[1] https://cs.chromium.org/chromium/src/chrome/browser/ui/app_list/app_list_syncable_service_factory.cc?rcl=3f0aa47f017d32154fe56e0b7aad6985a65ffa0f&l=91

[2] https://cs.chromium.org/chromium/src/chrome/browser/ui/browser.cc?rcl=3f0aa47f017d32154fe56e0b7aad6985a65ffa0f&l=390

xiyuan@, Thanks.

I am not sure why "File" and "Settings" are different to get those profiles.

Could you please be more specific about "Maybe add a guest session check to not redirect in such case."
What is "redirect". Thank you!

Extension apps work fine because they are not using Browser. Hence not subject to that CHECK().

> Could you please be more specific about "Maybe add a guest session check to not redirect in such case." What is "redirect".

I am thinking of something like the following:

content::BrowserContext* AppListSyncableServiceFactory::GetBrowserContextToUse(
    content::BrowserContext* context) const {
  Profile* const profile = Profile::FromBrowserContext(context);
  // No service if |context| is not a profile.
  if (!profile)
    return nullptr;

  // No service for system profile.
  if (profile->IsSystemProfile())
    return nullptr;
  
  // Use profile as-is for guest session.
  if (profile->IsGuestSession())
    return chrome::GetBrowserContextOwnInstanceInIncognito(context);

  // This matches the logic in ExtensionSyncServiceFactory, which uses the
  // orginal browser context.
  return chrome::GetBrowserContextRedirectedInIncognito(context);
}

Xiyuan@, the code in #6 works. I will upload a cl soon.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/25151c3490c0fc6d761527375e243d144a06aa2d

commit 25151c3490c0fc6d761527375e243d144a06aa2d
Author: wutao <wutao@chromium.org>
Date: Wed May 09 00:00:00 2018

cros: Use guest profile in AppListSyncableService

In guest session, we use two different profiles for "Suggested App" and
apps in Launcher. The later uses the profile of AppListSyncableService
which alwasy uses the original profile. However, the original profile is
not allowed in guest session.

This cl fixes this bug by returning guest profile in
AppListSyncableService in guest mode.

Bug:  840293 
Test: manual.
Change-Id: I30d9464597eaacba9a08560ca03e0679a9e906bf
Reviewed-on: https://chromium-review.googlesource.com/1049005
Commit-Queue: Tao Wu <wutao@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557014}
[modify] https://crrev.com/25151c3490c0fc6d761527375e243d144a06aa2d/chrome/browser/ui/app_list/app_list_syncable_service.cc
[modify] https://crrev.com/25151c3490c0fc6d761527375e243d144a06aa2d/chrome/browser/ui/app_list/app_list_syncable_service.h
[modify] https://crrev.com/25151c3490c0fc6d761527375e243d144a06aa2d/chrome/browser/ui/app_list/app_list_syncable_service_factory.cc

 Issue 839259  has been merged into this issue.