bluetooth: Register AdvMonitor App with app-root-path

This patch registers the AdvMonitor App with app-root-path so that
InterfacesAdded/InterfacesRemoved signals are emitted on the path
registered with RegisterMonitor method.

BUG=b:174055064
TEST=Run the AdvMonitor test batch and verify all tests PASS.
     $ test_that --board=eve-kernelnext --args
     "btpeer_host_list=100.90.103.30, 100.90.103.31"
     100.90.103.27 bluetooth_AdapterAdvMonitor

Change-Id: I618d0e41712c6c230ae50b184ac520c25606fd2e
Cq-Depend: chromium:2556037
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2560566
Reviewed-by: Yun-Hao Chung <howardchung@google.com>
Tested-by: Manish Mandlik <mmandlik@chromium.org>
Commit-Queue: Manish Mandlik <mmandlik@chromium.org>
diff --git a/client/cros/bluetooth/adv_monitor_helper.py b/client/cros/bluetooth/adv_monitor_helper.py
index 5161f8d..df92374 100644
--- a/client/cros/bluetooth/adv_monitor_helper.py
+++ b/client/cros/bluetooth/adv_monitor_helper.py
@@ -17,7 +17,6 @@
 DBUS_PROP_IFACE = 'org.freedesktop.DBus.Properties'
 
 BLUEZ_SERVICE_NAME = 'org.bluez'
-BLUEZ_MANAGER_PATH = '/'
 
 ADV_MONITOR_MANAGER_IFACE = 'org.bluez.AdvertisementMonitorManager1'
 ADV_MONITOR_IFACE = 'org.bluez.AdvertisementMonitor1'
@@ -275,16 +274,11 @@
         self.bus = bus
         self.mainloop = dbus_mainloop
         self.advmon_mgr = advmon_manager
-
         self.app_path = ADV_MONITOR_APP_BASE_PATH + str(app_id)
-        self.root_path = BLUEZ_MANAGER_PATH
 
         self.monitors = dict()
 
-        # BlueZ expects InterfacesAdded and InterfacesRemoved signals to be
-        # emitted on the root path. So, register the App object with root path
-        # to be able to emit those signals correctly.
-        super(AdvMonitorApp, self).__init__(self.bus, self.root_path)
+        super(AdvMonitorApp, self).__init__(self.bus, self.app_path)
 
 
     def get_app_path(self):