update_engine: Switch to chrome-dbus for client requests in update_engine

update_engine daemon acts as DBus client to send DBus calls to shill,
power_manager and chrome, and to listen for signals from shill, chrome
and login_manager. This patch migrates these calls and signals to use
chrome-dbus framework instead of dbus-glib.

All references to dbus-glib code are removed.

BUG=chromium:419827
TEST=Updated unittest. Deployed on a link device and tested interactions with shill and chromium.

Change-Id: I31b389e0d1690cccb115ff3b6539c876ba81bd0e
Reviewed-on: https://chromium-review.googlesource.com/290990
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Trybot-Ready: Alex Deymo <deymo@chromium.org>
diff --git a/connection_manager_interface.h b/connection_manager_interface.h
index aa04946..642f60f 100644
--- a/connection_manager_interface.h
+++ b/connection_manager_interface.h
@@ -7,8 +7,6 @@
 
 #include <base/macros.h>
 
-#include "update_engine/dbus_wrapper_interface.h"
-
 namespace chromeos_update_engine {
 
 enum class NetworkConnectionType {
@@ -37,10 +35,8 @@
   // Populates |out_type| with the type of the network connection
   // that we are currently connected and |out_tethering| with the estimate of
   // whether that network is being tethered.
-  virtual bool GetConnectionProperties(
-      DBusWrapperInterface* dbus_iface,
-      NetworkConnectionType* out_type,
-      NetworkTethering* out_tethering) const = 0;
+  virtual bool GetConnectionProperties(NetworkConnectionType* out_type,
+                                       NetworkTethering* out_tethering) = 0;
 
   // Returns true if we're allowed to update the system when we're
   // connected to the internet through the given network connection type and the