login: Allow QueryAdbSideload from patchpaneld

Allow patchpanel's user patchpaneld to call
QueryAdbSideload. permission_broker was supposed
to call QueryAdbSideload, but after iptables migration
(b/160130580), patchpanel is supposed to set iptables
rule for sideloading.

QueryAdbSideload is also used for ADB proxy to make it
start only when necessary (dev mode or sideloading on).

BUG=b:175167879
TEST=QueryAdbSideload can be run from
     patchpaneld;
TEST=dbus-send --system --type=method_call --dest=org.chromium.SessionManager \
        --print-reply /org/chromium/SessionManager \
        org.chromium.SessionManagerInterface.QueryAdbSideload

Change-Id: Ia703272ea27599f8321e71925b675d9eec5d5428
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2586574
Tested-by: Jason Jeremy Iman <jasongustaman@chromium.org>
Reviewed-by: Hugo Benichi <hugobenichi@google.com>
Reviewed-by: Victor Hsieh <victorhsieh@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
Commit-Queue: Jason Jeremy Iman <jasongustaman@chromium.org>
diff --git a/login_manager/SessionManager.conf b/login_manager/SessionManager.conf
index e273b29..2176325 100644
--- a/login_manager/SessionManager.conf
+++ b/login_manager/SessionManager.conf
@@ -155,7 +155,7 @@
            send_member="QueryAdbSideload"/>
   </policy>
 
-  <policy user="devbroker">
+  <policy user="patchpaneld">
     <allow send_destination="org.chromium.SessionManager"
            send_interface="org.chromium.SessionManagerInterface"
            send_member="QueryAdbSideload"/>