Implement RTP keepalive in native stack.

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 895 matching lines @@
 
 // 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,
 };
 
+struct RtpKeepAliveConfig {
+  // If no packet has been sent for |timeout_interval_ms|, send a keep-alive
+  // packet. The keep-alive packet is an empty (no payload) RTP packet with a
+  // payload type of 20 as long as the other end has not negotiated the use of
+  // this value. If this value has already been negotiated, then some other
+  // unused static payload type from table 5 of RFC 3551 shall be used and set
+  // in |payload_type|.
+  int64_t timeout_interval_ms = -1;
+  uint8_t payload_type = 20;
+};
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_TYPES_H_