Remove candidates when doing continual gathering

webrtc/api/jsepicecandidate.h

Index: webrtc/api/jsepicecandidate.h
diff --git a/webrtc/api/jsepicecandidate.h b/webrtc/api/jsepicecandidate.h
index 529b2a7756de8ea0ebf33e714fb6e63eb04176a6..47b8b83902bf5302fd04e60e11d5f05254246885 100644
--- a/webrtc/api/jsepicecandidate.h
+++ b/webrtc/api/jsepicecandidate.h
@@ -21,7 +21,7 @@
 
 namespace webrtc {
 
-class JsepIceCandidate : public IceCandidateInterface {
+class JsepIceCandidate : public rtc::RefCountedObject<IceCandidateInterface> {
  public:
   JsepIceCandidate(const std::string& sdp_mid, int sdp_mline_index);
   JsepIceCandidate(const std::string& sdp_mid, int sdp_mline_index,
@@ -70,6 +70,9 @@ class JsepCandidateCollection : public IceCandidateCollection {
   virtual const IceCandidateInterface* at(size_t index) const {
     return candidates_[index];
   }
+  // Removes candidates that have a matching address and protocol.
+  // Returns the number of candidates that were removed.
+  int remove(const IceCandidateInterface* candidate);
 
  private:
   std::vector<JsepIceCandidate*> candidates_;