Issue 861979  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6ea959c96b1e5eb62c718285413cdeeb26a78a0b

commit 6ea959c96b1e5eb62c718285413cdeeb26a78a0b
Author: Luciano Pacheco <lucmult@chromium.org>
Date: Wed Jul 11 02:44:31 2018

Fix Downloads disappearing upon refresh

During tree update, DirectoryTree expects the NavigationModelItem to be
the same instance to be able to find the item in the tree, so this CL
changes NavigationListModel to not create a new model instance on
|orderAndNestItems_|.

Add unittest to VolumeEntry for rootEntry null and resolveDisplayRoot.

Add unittest to NavigationListModel to check that MyFiles model is the
same across multiple calls to |orderAndNestItems_|.

Add integration_test to cover the tree update when an USB volume is
mounted.

Fix |isDescendantyEntry| to use const instead of let and to work with
VolumeEntry with non-resolved rootEntry.

Bug:  861978 
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: I92f76749dd56a134c4b33517dfa3333ed4f01cca
Reviewed-on: https://chromium-review.googlesource.com/1130957
Reviewed-by: Sasha Morrissey <sashab@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574046}
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/chrome/browser/chromeos/file_manager/file_manager_browsertest.cc
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/ui/file_manager/file_manager/common/js/files_app_entry_types.js
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/ui/file_manager/file_manager/common/js/files_app_entry_types_unittest.js
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/ui/file_manager/file_manager/common/js/util.js
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/ui/file_manager/file_manager/foreground/js/navigation_list_model.js
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/ui/file_manager/file_manager/foreground/js/navigation_list_model_unittest.js
[modify] https://crrev.com/6ea959c96b1e5eb62c718285413cdeeb26a78a0b/ui/file_manager/integration_tests/file_manager/my_files.js

It was fixed on the commit above.