Refactoring

(cherry picked from commit fbed4d18be36b8d1d63301406789b1b0a93c5c65)
services: don't clear wallpaper when SystemUI
disconnects.

When we restart SystemUI (or the user), sometimes
the wallpaper would get cleared. This patch just
captures its originating component and
if that is our SystemUI component, ignore the event.

Change-Id: I3e159dc2c013e7d7e552e3c0cef55e3ab970ca87
Signed-off-by: Roman Birg <romanbirg@gmail.com>
(cherry picked from commit 3cc369cbe320cbc919c23a27853e3592ce9a9a06)