use push messaging in cache invalidation xmpp channel

jingle/notifier/listener/notification_defines.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef JINGLE_NOTIFIER_LISTENER_NOTIFICATION_DEFINES_H_
 #define JINGLE_NOTIFIER_LISTENER_NOTIFICATION_DEFINES_H_
 
 #include <string>
 #include <vector>
 
 namespace notifier {
 
 struct Subscription {
   // The name of the channel to subscribe to; usually but not always
   // a URL.
   std::string channel;
   // A sender, which could be a domain or a bare JID, from which we
   // will accept pushes.
   std::string from;
 };
 
 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 {
   // 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;
 
   std::string ToString() const;
 };
 
 }  // namespace notifier
 
 #endif  // JINGLE_NOTIFIER_LISTENER_NOTIFICATION_DEFINES_H_