Reland the CL to remove candidates when doing continual gathering

webrtc/api/peerconnection.h

Index: webrtc/api/peerconnection.h
diff --git a/webrtc/api/peerconnection.h b/webrtc/api/peerconnection.h
index 3b0d558cfc604db38ba38a62754ed2ada6ce70df..d715ecdf73d45574a1383a2c66c8f6e5fcaa8af9 100644
--- a/webrtc/api/peerconnection.h
+++ b/webrtc/api/peerconnection.h
@@ -132,6 +132,8 @@ class PeerConnection : public PeerConnectionInterface,
   bool SetConfiguration(
       const PeerConnectionInterface::RTCConfiguration& config) override;
   bool AddIceCandidate(const IceCandidateInterface* candidate) override;
+  bool RemoveIceCandidates(
+      const std::vector<cricket::Candidate>& candidates) override;
 
   void RegisterUMAObserver(UMAObserver* observer) override;
 
@@ -187,6 +189,8 @@ class PeerConnection : public PeerConnectionInterface,
   void OnIceConnectionChange(IceConnectionState new_state) override;
   void OnIceGatheringChange(IceGatheringState new_state) override;
   void OnIceCandidate(const IceCandidateInterface* candidate) override;
+  void OnIceCandidatesRemoved(
+      const std::vector<cricket::Candidate>& candidates) override;
   void OnIceConnectionReceivingChange(bool receiving) override;
 
   // Signals from WebRtcSession.