[glibmm] Gio::DBus::Proxy: Derive from (and implement) Gio::DBus::Interface.

[Murray Cumming <murrayc src gnome org>]

commit 6a172a3335be19fb87c6774b738b4655ffd27e73
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Dec 2 12:52:55 2016 +0100

    Gio::DBus::Proxy: Derive from (and implement) Gio::DBus::Interface.

 gio/src/dbusinterface.hg |    2 --
 gio/src/dbusproxy.hg     |    5 ++++-
 2 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/gio/src/dbusinterface.hg b/gio/src/dbusinterface.hg
index ad11ea1..485d2b5 100644
--- a/gio/src/dbusinterface.hg
+++ b/gio/src/dbusinterface.hg
@@ -38,8 +38,6 @@ class Object;
 
 _GMMPROC_EXTRA_NAMESPACE(DBus)
 
-//TODO: Have Proxy derive from this interface when there is an ABI break.
-
 /** Interface - Base type for D-Bus interfaces.
  * The Interface type is the base type for D-Bus interfaces both on the service
  * side (see InterfaceSkeleton) and client side (see Proxy).
diff --git a/gio/src/dbusproxy.hg b/gio/src/dbusproxy.hg
index 2e3729f..8ac5083 100644
--- a/gio/src/dbusproxy.hg
+++ b/gio/src/dbusproxy.hg
@@ -20,6 +20,7 @@
 #include <glibmm/object.h>
 #include <giomm/asyncresult.h>
 #include <giomm/dbusintrospection.h>
+#include <giomm/dbusinterface.h>
 #include <giomm/initable.h>
 #include <giomm/asyncinitable.h>
 #include <giomm/dbusconnection.h>
@@ -66,11 +67,13 @@ _WRAP_ENUM(ProxyFlags, GDBusProxyFlags, s#^DBUS_##, NO_GTYPE)
 class Proxy
 : public Glib::Object,
   public Initable,
-  public AsyncInitable
+  public AsyncInitable,
+  public Interface
 {
   _CLASS_GOBJECT(Proxy, GDBusProxy, G_DBUS_PROXY, Glib::Object, GObject)
   _IMPLEMENTS_INTERFACE(Initable)
   _IMPLEMENTS_INTERFACE(AsyncInitable)
+  _IMPLEMENTS_INTERFACE(DBus::Interface)
 
 protected: