The crash happens here: https://cs.chromium.org/chromium/src/ash/app_list/views/apps_grid_view.cc?type=cs&q=item_list_-%3ERemo&g=0&l=487

The item list exists, but does not contains the AppsGridView as observer.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8a961977c3092f16967d37efd898b8c434a58033

commit 8a961977c3092f16967d37efd898b8c434a58033
Author: Weidong Guo <weidongg@chromium.org>
Date: Tue Oct 16 02:58:44 2018

Fix crash of app list in multi-profile

Background:
After switching to another account, the item list for folder gets
destructed, but |items_grid_view_| still has stale pointer to the
object. When opening a folder, AppsGridView::SetItemList() will try
to remove observer from the stale object, thus causing the crash.

Changes:
Notify observers when the folder item will be deleted.

Bug:  891430 
Change-Id: Id2957b594022321feaf6ee3cf402af318ddf169a
Reviewed-on: https://chromium-review.googlesource.com/c/1282033
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599826}
[modify] https://crrev.com/8a961977c3092f16967d37efd898b8c434a58033/ash/app_list/model/app_list_item_list.cc
[modify] https://crrev.com/8a961977c3092f16967d37efd898b8c434a58033/ash/app_list/model/app_list_item_list.h
[modify] https://crrev.com/8a961977c3092f16967d37efd898b8c434a58033/ash/app_list/model/app_list_model.cc