use push messaging in cache invalidation xmpp channel

jingle/notifier/listener/notification_defines.h

Index: jingle/notifier/listener/notification_defines.h
===================================================================
--- jingle/notifier/listener/notification_defines.h	(revision 119260)
+++ jingle/notifier/listener/notification_defines.h	(working copy)
@@ -21,9 +21,24 @@
 
 typedef std::vector<Subscription> SubscriptionList;
 
+// A structure representing a <recipient/> block within a push message.
+struct Recipient {
+  // The bare jid of the recipient.
+  std::string to;
+  // User-specific data for the recipient.
+  std::string user_specific_data;
+};
+
+typedef std::vector<Recipient> RecipientList;
+
 struct Notification {
+  Notification();
+  ~Notification();
+
   // The channel the notification is coming in on.
   std::string channel;
+  // Recipients for this notification (may be empty).
+  RecipientList recipients;
   // The notification data payload.
   std::string data;