ash: Fix duplicate OnActiveUserPrefServiceChanged call

SessionObserver::OnActiveUserPrefServiceChanged should be called
only when the active user prefs is actually changed. Fix the
session order change handling code to check that before sending
out the notification.

Bug: 1028376
Change-Id: Ice203557c9e95628a9bae44b4624d5d7f2b0c0f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1951572
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722037}
2 files changed