core: separate PropertiesChanged signal XML

Which requires that we turn it into a GInterface that MMModemBase
can implement, because dbus-glib does not allow attaching more
than one introspection glue structure to an object at a time.

Also implement the standard D-Bus properties changed signal.

introspection/Makefile.am

@@ -15,4 +15,5 @@ EXTRA_DIST = \
 	mm-modem-simple.xml \
 	mm-serial-error.xml \
 	mm-modem-location.xml \
-	mm-modem-gsm-ussd.xml
+	mm-modem-gsm-ussd.xml \
+	mm-properties-changed.xml

introspection/all.xml

@@ -35,6 +35,7 @@
   <xi:include href="mm-modem-gsm-sms.xml"/>
   <xi:include href="mm-modem-gsm-hso.xml"/>
   <xi:include href="mm-modem-gsm-ussd.xml"/>
+  <xi:include href="mm-properties-changed.xml"/>
 
   <xi:include href="mm-serial-error.xml"/>
   <xi:include href="mm-modem-error.xml"/>

introspection/mm-modem.xml

@@ -2,24 +2,6 @@
 
 <node name="/" xmlns:tp="http://telepathy.freedesktop.org/wiki/DbusSpec#extensions-v0">
 
-  <interface name="org.freedesktop.DBus.Properties">
-    <signal name="MmPropertiesChanged">
-      <tp:docstring>
-	One or more properties' values changed.
-      </tp:docstring>
-      <arg name="interface" type="s">
-	<tp:docstring>
-	  The D-Bus interface of the changed properties.
-	</tp:docstring>
-      </arg>
-      <arg name="properties" type="a{sv}">
-	<tp:docstring>
-	  The changed property names and their new values.
-	</tp:docstring>
-      </arg>
-    </signal>
-  </interface>
-
   <interface name="org.freedesktop.ModemManager.Modem">
     <method name="Enable">
       <tp:docstring>

introspection/mm-properties-changed.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<node name="/" xmlns:tp="http://telepathy.freedesktop.org/wiki/DbusSpec#extensions-v0">
+  <interface name="org.freedesktop.DBus.Properties">
+    <signal name="MmPropertiesChanged">
+      <tp:docstring>
+	One or more properties' values changed.
+      </tp:docstring>
+      <arg name="interface" type="s">
+	<tp:docstring>
+	  The D-Bus interface of the changed properties.
+	</tp:docstring>
+      </arg>
+      <arg name="properties" type="a{sv}">
+	<tp:docstring>
+	  The changed property names and their new values.
+	</tp:docstring>
+      </arg>
+    </signal>
+
+    <signal name="PropertiesChanged">
+      <tp:docstring>
+	One or more properties value changed; this signal implements the
+	D-Bus specification's PropertiesChanged signal.
+      </tp:docstring>
+      <arg name="interface" type="s">
+	<tp:docstring>
+	  The D-Bus interface of the changed properties.
+	</tp:docstring>
+      </arg>
+      <arg name="changed_properties" type="a{sv}">
+	<tp:docstring>
+	  The changed property names and their new values.
+	</tp:docstring>
+      </arg>
+      <arg name="invalidated_properties" type="as">
+	<tp:docstring>
+	  Properties which are now invalid, but for which the new value is not
+	  emitted in this signal.  Clients interested in these properties should
+	  issue a Get request for them to retrieve the new value.
+	</tp:docstring>
+      </arg>
+    </signal>
+  </interface>
+</node>