Add remoting::protocol::NetworkStateObserver interface.

remoting/protocol/video_channel_state_observer.h

Index: remoting/protocol/video_channel_state_observer.h
diff --git a/remoting/protocol/video_channel_state_observer.h b/remoting/protocol/video_channel_state_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..d5efdef1ee770b338c74b62d6423eabf9bbb2744
--- /dev/null
+++ b/remoting/protocol/video_channel_state_observer.h
@@ -0,0 +1,26 @@
+// 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_VIDEO_CHANNEL_STATE_OBSERVER_H_
+#define REMOTING_PROTOCOL_VIDEO_CHANNEL_STATE_OBSERVER_H_
+
+#include "base/time/time.h"
+
+namespace remoting {
+namespace protocol {
+
+class VideoChannelStateObserver {
+ public:
+  virtual void OnKeyFrameRequested() = 0;
+  virtual void OnChannelParameters(int packet_loss, base::TimeDelta rtt) = 0;
+  virtual void OnTargetBitrateChanged(int bitrate_kbps) = 0;
+
+ protected:
+  virtual ~VideoChannelStateObserver() {}
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_VIDEO_CHANNEL_STATE_OBSERVER_H_