Reland the CL to remove candidates when doing continual gathering

webrtc/p2p/base/transport.cc

Index: webrtc/p2p/base/transport.cc
diff --git a/webrtc/p2p/base/transport.cc b/webrtc/p2p/base/transport.cc
index 17d05adc23216ecf5b5644a55da2dfa346c414e2..b8d98100cf3af1f8b93b98e0362c15132ece9cd2 100644
--- a/webrtc/p2p/base/transport.cc
+++ b/webrtc/p2p/base/transport.cc
@@ -294,6 +294,22 @@ bool Transport::VerifyCandidate(const Candidate& cand, std::string* error) {
     }
   }
 
+  if (!HasChannel(cand.component())) {
+    *error = "Candidate has an unknown component: " + cand.ToString() +
+             " for content: " + name();
+    return false;
+  }
+
+  return true;
+}
+
+bool Transport::VerifyCandidates(const Candidates& candidates,
+                                 std::string* error) {
+  for (const Candidate& candidate : candidates) {
+    if (!VerifyCandidate(candidate, error)) {
+      return false;
+    }
+  }
   return true;
 }
 
@@ -318,16 +334,9 @@ bool Transport::GetStats(TransportStats* stats) {
 bool Transport::AddRemoteCandidates(const std::vector<Candidate>& candidates,
                                     std::string* error) {
   ASSERT(!channels_destroyed_);
-  // Verify each candidate before passing down to transport layer.
-  for (const Candidate& cand : candidates) {
-    if (!VerifyCandidate(cand, error)) {
-      return false;
-    }
-    if (!HasChannel(cand.component())) {
-      *error = "Candidate has unknown component: " + cand.ToString() +
-               " for content: " + name();
-      return false;
-    }
+  // Verify each candidate before passing down to the transport layer.
+  if (!VerifyCandidates(candidates, error)) {
+    return false;
   }
 
   for (const Candidate& candidate : candidates) {
@@ -339,6 +348,23 @@ bool Transport::AddRemoteCandidates(const std::vector<Candidate>& candidates,
   return true;
 }
 
+bool Transport::RemoveRemoteCandidates(const std::vector<Candidate>& candidates,
+                                       std::string* error) {
+  ASSERT(!channels_destroyed_);
+  // Verify each candidate before passing down to the transport layer.
+  if (!VerifyCandidates(candidates, error)) {
+    return false;
+  }
+
+  for (const Candidate& candidate : candidates) {
+    TransportChannelImpl* channel = GetChannel(candidate.component());
+    if (channel != nullptr) {
+      channel->RemoveRemoteCandidate(candidate);
+    }
+  }
+  return true;
+}
+
 bool Transport::ApplyLocalTransportDescription(TransportChannelImpl* ch,
                                                std::string* error_desc) {
   ch->SetIceCredentials(local_description_->ice_ufrag,