Remove candidates when doing continual gathering

webrtc/api/jsepsessiondescription.cc

Index: webrtc/api/jsepsessiondescription.cc
diff --git a/webrtc/api/jsepsessiondescription.cc b/webrtc/api/jsepsessiondescription.cc
index b47114b9bcd052979f13a19bdea35d3faae6efc5..ac9b6afbd829aa1c743c6146196d18cb1e3a6cfe 100644
--- a/webrtc/api/jsepsessiondescription.cc
+++ b/webrtc/api/jsepsessiondescription.cc
@@ -137,6 +137,28 @@ bool JsepSessionDescription::AddCandidate(
   return true;
 }
 
+int JsepSessionDescription::RemoveCandidate(
+    const IceCandidateInterface* candidate) {
+  if (!candidate || candidate->sdp_mline_index() < 0) {
+    return 0;
+  }
+  size_t mediasection_index = 0;
+  if (!GetMediasectionIndex(candidate, &mediasection_index) ||
+      mediasection_index >= number_of_mediasections()) {
+    return 0;
+  }
+  return candidate_collection_[mediasection_index].remove(candidate);
+}
+
+int JsepSessionDescription::RemoveCandidates(
+    const std::vector<IceCandidateInterfaceRefPtr>& candidates) {
+  int num_removed = 0;
+  for (auto candidate : candidates) {
+    num_removed += RemoveCandidate(candidate.get());
+  }
+  return num_removed;
+}
+
 size_t JsepSessionDescription::number_of_mediasections() const {
   if (!description_)
     return 0;