Reland the CL to remove candidates when doing continual gathering

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 2185fb3aad7eb1d4947a36e64bdfe44367007246..bbf3e5c484b0302672ea889665ec4ec0ac285134 100644
--- a/webrtc/p2p/base/dtlstransportchannel.cc
+++ b/webrtc/p2p/base/dtlstransportchannel.cc
@@ -113,6 +113,8 @@ DtlsTransportChannelWrapper::DtlsTransportChannelWrapper(
       this, &DtlsTransportChannelWrapper::OnGatheringState);
   channel_->SignalCandidateGathered.connect(
       this, &DtlsTransportChannelWrapper::OnCandidateGathered);
+  channel_->SignalCandidatesRemoved.connect(
+      this, &DtlsTransportChannelWrapper::OnCandidatesRemoved);
   channel_->SignalRoleConflict.connect(this,
       &DtlsTransportChannelWrapper::OnRoleConflict);
   channel_->SignalRouteChange.connect(this,
@@ -613,6 +615,13 @@ void DtlsTransportChannelWrapper::OnCandidateGathered(
   SignalCandidateGathered(this, c);
 }
 
+void DtlsTransportChannelWrapper::OnCandidatesRemoved(
+    TransportChannelImpl* channel,
+    const Candidates& candidates) {
+  ASSERT(channel == channel_);
+  SignalCandidatesRemoved(this, candidates);
+}
+
 void DtlsTransportChannelWrapper::OnRoleConflict(
     TransportChannelImpl* channel) {
   ASSERT(channel == channel_);