Remove candidates when doing continual gathering

talk/app/webrtc/jsep.h

Index: talk/app/webrtc/jsep.h
diff --git a/talk/app/webrtc/jsep.h b/talk/app/webrtc/jsep.h
index c12ab85f346c10467b49cd2d3dc4dc69a4d347cc..259e7000fb86f96c052be4d8ab7c09476990b5b2 100644
--- a/talk/app/webrtc/jsep.h
+++ b/talk/app/webrtc/jsep.h
@@ -87,6 +87,9 @@ class IceCandidateCollection {
   // Returns true if an equivalent |candidate| exist in the collection.
   virtual bool HasCandidate(const IceCandidateInterface* candidate) const = 0;
   virtual const IceCandidateInterface* at(size_t index) const = 0;
+  // Removes candidates that have a matching address and protocol.
+  // Returns the number of candidates that were removed.
+  virtual int remove(const IceCandidateInterface* candidate) = 0;
 };
 
 // Class representation of a Session description.
@@ -112,6 +115,9 @@ class SessionDescriptionInterface {
   // Returns false if the session description does not have a media section that
   // corresponds to the |candidate| label.
   virtual bool AddCandidate(const IceCandidateInterface* candidate) = 0;
+  // Removes the candidate that has a matching 5-tuple from the description.
+  // Returns true if a candidate is found and removed.
+  virtual bool RemoveCandidate(const IceCandidateInterface* candidate) = 0;
   // Returns the number of m- lines in the session description.
   virtual size_t number_of_mediasections() const = 0;
   // Returns a collection of all candidates that belong to a certain m-line