Remove candidates when doing continual gathering

webrtc/api/jsepicecandidate.cc

Index: webrtc/api/jsepicecandidate.cc
diff --git a/webrtc/api/jsepicecandidate.cc b/webrtc/api/jsepicecandidate.cc
index 2aabcb83498ead96000f9624b423a21102516bfb..ea563991578d63399b89418690e18734b314f602 100644
--- a/webrtc/api/jsepicecandidate.cc
+++ b/webrtc/api/jsepicecandidate.cc
@@ -79,4 +79,14 @@ bool JsepCandidateCollection::HasCandidate(
   return ret;
 }
 
+size_t JsepCandidateCollection::remove(const cricket::Candidate& candidate) {
+  size_t original_size = candidates_.size();
+  auto new_end = std::remove_if(
+      candidates_.begin(), candidates_.end(), [candidate](JsepIceCandidate* c) {
+        return candidate.MatchesForRemoval(c->candidate());
+      });
+  candidates_.erase(new_end, candidates_.end());
+  return original_size - candidates_.size();
+}
+
 }  // namespace webrtc