DTLS-SRTP set up is bypassed when the channel has been writable.

talk/session/media/srtpfilter.cc

 /*
  * libjingle
  * Copyright 2009 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 432 matching lines @@
     applied_recv_params_ = recv_params;
   } else {
     LOG(LS_WARNING) << "Failed to apply negotiated SRTP parameters";
   }
   return ret;
 }
 
 bool SrtpFilter::ResetParams() {
   offer_params_.clear();
   state_ = ST_INIT;
+  (void)send_session_.release();
+  (void)recv_session_.release();
+  (void)send_rtcp_session_.release();
+  (void)recv_rtcp_session_.release();
   LOG(LS_INFO) << "SRTP reset to init state";
   return true;
 }
 
 bool SrtpFilter::ParseKeyParams(const std::string& key_params,
                                 uint8_t* key,
                                 int len) {
   // example key_params: "inline:YUJDZGVmZ2hpSktMbW9QUXJzVHVWd3l6MTIzNDU2"
 
   // Fail if key-method is wrong.
@@ skipping 478 matching lines @@
   SrtpNotAvailable(__FUNCTION__);
 }
 
 void SrtpStat::HandleSrtpResult(const SrtpStat::FailureKey& key) {
   SrtpNotAvailable(__FUNCTION__);
 }
 
 #endif  // HAVE_SRTP
 
 }  // namespace cricket