Fix build break in google3 import

talk/session/media/srtpfilter.cc

Index: talk/session/media/srtpfilter.cc
diff --git a/talk/session/media/srtpfilter.cc b/talk/session/media/srtpfilter.cc
index 7961a7ba06de370ddd822e03a53f9b1f000fc39b..a200a3c4c2c798dd6e834ed4c05213ed78d28229 100644
--- a/talk/session/media/srtpfilter.cc
+++ b/talk/session/media/srtpfilter.cc
@@ -450,10 +450,10 @@ bool SrtpFilter::ApplyParams(const CryptoParams& send_params,
 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();
+  send_session_ = nullptr;
+  recv_session_ = nullptr;
+  send_rtcp_session_ = nullptr;
+  recv_rtcp_session_ = nullptr;
   LOG(LS_INFO) << "SRTP reset to init state";
   return true;
 }