Add remoting::protocol::NetworkStateObserver interface.

remoting/protocol/network_state_observer.h

+// Copyright 2016 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_PROTOCOL_NETWORK_STATE_OBSERVER_H_
+#define REMOTING_PROTOCOL_NETWORK_STATE_OBSERVER_H_
+
+#include "base/time/time.h"
+
+namespace remoting {
+namespace protocol {
+
+class NetworkStateObserver {
+ public:
+  virtual void OnKeyFrameRequested() = 0;
+  virtual void OnChannelParameters(int packet_loss, base::TimeDelta rtt) = 0;
+  virtual void OnTargetBitrateChanged(int bitrate_kbps) = 0;
+
+ protected:
+  virtual ~NetworkStateObserver() {}
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_NETWORK_STATE_OBSERVER_H_