Added class to subscribe to GCD notifications over XMPP.

remoting/signaling/gcd_notification_subscriber.h

Index: remoting/signaling/gcd_notification_subscriber.h
diff --git a/remoting/signaling/gcd_notification_subscriber.h b/remoting/signaling/gcd_notification_subscriber.h
new file mode 100644
index 0000000000000000000000000000000000000000..f84a402d0a344d7ba6b5f97a3364bc222acc1c06
--- /dev/null
+++ b/remoting/signaling/gcd_notification_subscriber.h
@@ -0,0 +1,44 @@
+// Copyright 2015 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 REMOTING_HOST_GCD_NOTIFICATION_SUBSCRIBER_H_
+#define REMOTING_HOST_GCD_NOTIFICATION_SUBSCRIBER_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "remoting/signaling/signal_strategy.h"
+
+namespace remoting {
+
+class IqSender;
+class IqRequest;
+
+// An object that subscribes to notifications from GCD using an XMPP
+// channel.  No actual notifications are used, but the subscription is
+// necessary in order for GCD to consider a device online.
+class GcdNotificationSubscriber : public SignalStrategy::Listener {
+ public:
+  GcdNotificationSubscriber(SignalStrategy* signal_strategy);
+  ~GcdNotificationSubscriber() override;
+
+ private:
+  // SignalStrategy::Listener interface.
+  void OnSignalStrategyStateChange(SignalStrategy::State state) override;
+  bool OnSignalStrategyIncomingStanza(const buzz::XmlElement* stanza) override;
+
+  void OnSubscriptionResult(IqRequest* request,
+                            const buzz::XmlElement* response);
+
+  SignalStrategy* signal_strategy_;
+  scoped_ptr<IqSender> iq_sender_;
+  scoped_ptr<IqRequest> iq_request_;
+
+  DISALLOW_COPY_AND_ASSIGN(GcdNotificationSubscriber);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_GCD_NOTIFICATION_SUBSCRIBER_H_