The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898

commit bbe5cb1a8c2c0d01eadecd2510e054efe91fb898
Author: James Cook <jamescook@chromium.org>
Date: Tue Aug 08 18:32:21 2017

cros: Refine local state prefs usage in ash

On mash the ash process has to connect to the mojo pref service before
local state prefs are available, which means there is a window during
startup where they are not available. Classic ash allows immediate
access to local state prefs, which makes it easy to write code that
works in classic but not in mash.

Make classic ash and mash local state behavior more similar:
* Add ShellObserver::OnLocalStatePrefServiceReady()
* Make Shell::GetLocalStatePrefService() return null until that observer
method is fired
* Eliminate ShellDelegate::GetLocalStatePrefService() so that code in
classic ash can't use the delegate to get the PrefService too early
* Fix PaletteTray to use the new approach

WallpaperController will need to be fixed in a separate CL because
wallpaper also has other differences between classic and mash.

Bug:  752671 ,  751191 ,  752997 
Test: added to ash_unittests
Change-Id: Iead4ae3f4c2fc4ed065a0eb9ebae7668dadc6c25
Reviewed-on: https://chromium-review.googlesource.com/604478
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#492706}
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/mus/shell_delegate_mus.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/mus/shell_delegate_mus.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell/shell_delegate_impl.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell/shell_delegate_impl.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell_delegate.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell_observer.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell_test_api.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell_test_api.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/shell_unittest.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/system/palette/palette_tray.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/system/palette/palette_tray.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/system/palette/palette_tray_unittest.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/test_shell_delegate.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/ash/test_shell_delegate.h
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/chrome/browser/ui/ash/ash_init.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/chrome/browser/ui/ash/chrome_shell_delegate.cc
[modify] https://crrev.com/bbe5cb1a8c2c0d01eadecd2510e054efe91fb898/chrome/browser/ui/ash/chrome_shell_delegate.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a853cd85ddccd0d99e2bcd1b8fa06bf786404754

commit a853cd85ddccd0d99e2bcd1b8fa06bf786404754
Author: Sam McNally <sammc@chromium.org>
Date: Wed Aug 30 01:55:10 2017

Unify classic ash and mash access to local state prefs.

Change classic ash to always use mojo to access local state prefs,
matching mash.

Change-Id: Ifd45ac5b2fa832a1a16efeaac4e9be91a1b2b266
Bug:  751191 
Reviewed-on: https://chromium-review.googlesource.com/616505
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#498337}
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/shell.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/shell.h
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/shell_unittest.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/system/palette/palette_tray.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/system/palette/palette_tray_unittest.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/test/ash_test_base.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/test/ash_test_base.h
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/test/ash_test_helper.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/test/ash_test_helper.h
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/wallpaper/wallpaper_controller.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/ash/wallpaper/wallpaper_controller.h
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/chrome/browser/chrome_content_browser_manifest_overlay.json
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/chrome/browser/chromeos/preferences.cc
[modify] https://crrev.com/a853cd85ddccd0d99e2bcd1b8fa06bf786404754/chrome/browser/ui/ash/ash_init.cc

Fixed in Sam's CL above.