Remove webrtc/stream.h and unutilized inheritance.

webrtc/common_types.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 862 matching lines @@
   virtual ~StreamDataCountersCallback() {}
 
   virtual void DataCountersUpdated(const StreamDataCounters& counters,
                                    uint32_t ssrc) = 0;
 };
 
 // RTCP mode to use. Compound mode is described by RFC 4585 and reduced-size
 // RTCP mode is described by RFC 5506.
 enum class RtcpMode { kOff, kCompound, kReducedSize };
 
+enum NetworkState {
+  kNetworkUp,
+  kNetworkDown,
+};
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_TYPES_H_