Ping backup connection at a slower rate

webrtc/p2p/base/transport.h

 /*
  *  Copyright 2004 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 122 matching lines @@
 
 // Information about the stats of a transport.
 struct TransportStats {
   std::string transport_name;
   TransportChannelStatsList channel_stats;
 };
 
 // Information about ICE configuration.
 struct IceConfig {
   // The ICE connection receiving timeout value.
+  // TODO(honghaiz): Remove suffix _ms to be consistent.
   int receiving_timeout_ms = -1;
+  // Time interval in milliseconds to ping a backup connection when the ICE
+  // channel is strongly connected.
+  int backup_connection_ping_interval = -1;
   // If true, the most recent port allocator session will keep on running.
   bool gather_continually = false;
 };
 
 bool BadTransportDescription(const std::string& desc, std::string* err_desc);
 
 bool IceCredentialsChanged(const std::string& old_ufrag,
                            const std::string& old_pwd,
                            const std::string& new_ufrag,
                            const std::string& new_pwd);
@@ skipping 159 matching lines @@
 
   ChannelMap channels_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(Transport);
 };
 
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_TRANSPORT_H_