Add flakiness check if there is no received packets in a certain period.

webrtc/p2p/base/dtlstransportchannel.cc

Index: webrtc/p2p/base/dtlstransportchannel.cc
diff --git a/webrtc/p2p/base/dtlstransportchannel.cc b/webrtc/p2p/base/dtlstransportchannel.cc
index e73cf688bda12420e9745d034bec53e586eecfa6..f56001ba4d3a51943e414bad8fa97f9f86916f80 100644
--- a/webrtc/p2p/base/dtlstransportchannel.cc
+++ b/webrtc/p2p/base/dtlstransportchannel.cc
@@ -118,6 +118,8 @@ DtlsTransportChannelWrapper::DtlsTransportChannelWrapper(
       &DtlsTransportChannelWrapper::OnRouteChange);
   channel_->SignalConnectionRemoved.connect(this,
       &DtlsTransportChannelWrapper::OnConnectionRemoved);
+  channel_->SignalReceivingState.connect(this,
+      &DtlsTransportChannelWrapper::OnReceivingState);
 }
 
 DtlsTransportChannelWrapper::~DtlsTransportChannelWrapper() {
@@ -456,6 +458,18 @@ void DtlsTransportChannelWrapper::OnWritableState(TransportChannel* channel) {
   }
 }
 
+void DtlsTransportChannelWrapper::OnReceivingState(TransportChannel* channel) {
+  ASSERT(rtc::Thread::Current() == worker_thread_);
+  ASSERT(channel == channel_);
+  LOG_J(LS_VERBOSE, this)
+      << "DTLSTransportChannelWrapper: channel receiving state changed to "
+      << channel_->receiving();
+  if (dtls_state_ == STATE_NONE || dtls_state_ == STATE_OPEN) {
+    // Note: SignalReceivingState fired by set_receiving.
+    set_receiving(channel_->receiving());
+  }
+}
+
 void DtlsTransportChannelWrapper::OnReadPacket(
     TransportChannel* channel, const char* data, size_t size,
     const rtc::PacketTime& packet_time, int flags) {