Remove candidates when doing continual gathering

talk/app/webrtc/webrtcsdp.cc

Index: talk/app/webrtc/webrtcsdp.cc
diff --git a/talk/app/webrtc/webrtcsdp.cc b/talk/app/webrtc/webrtcsdp.cc
index f5fb7f78e3334edd7f320d6f3e89f49b25132c4f..70bde6c24220002d9f99c639a46b9641e171d5f8 100644
--- a/talk/app/webrtc/webrtcsdp.cc
+++ b/talk/app/webrtc/webrtcsdp.cc
@@ -169,8 +169,7 @@ static const char kValueConference[] = "conference";
 // Candidate
 static const char kCandidateHost[] = "host";
 static const char kCandidateSrflx[] = "srflx";
-// TODO: How to map the prflx with circket candidate type
-// static const char kCandidatePrflx[] = "prflx";
+static const char kCandidatePrflx[] = "prflx";
 static const char kCandidateRelay[] = "relay";
 static const char kTcpCandidateType[] = "tcptype";
 
@@ -1029,6 +1028,8 @@ bool ParseCandidate(const std::string& message, Candidate* candidate,
     candidate_type = cricket::STUN_PORT_TYPE;
   } else if (type == kCandidateRelay) {
     candidate_type = cricket::RELAY_PORT_TYPE;
+  } else if (type == kCandidatePrflx) {
+    candidate_type = cricket::PRFLX_PORT_TYPE;
   } else {
     return ParseFailed(first_line, "Unsupported candidate type.", error);
   }
@@ -1741,6 +1742,11 @@ void BuildCandidate(const std::vector<Candidate>& candidates,
       type = kCandidateSrflx;
     } else if (it->type() == cricket::RELAY_PORT_TYPE) {
       type = kCandidateRelay;
+    } else if (it->type() == cricket::PRFLX_PORT_TYPE) {
+      type = kCandidatePrflx;
+      // Peer reflexive candidate should only be signaled with priority 0 for
+      // being removed.
+      ASSERT(it->priority() == 0);
     } else {
       ASSERT(false);
       // Never write out candidates if we don't know the type.