Remove candidates when doing continual gathering

webrtc/p2p/base/candidate.h

Index: webrtc/p2p/base/candidate.h
diff --git a/webrtc/p2p/base/candidate.h b/webrtc/p2p/base/candidate.h
index ddfeef0323a31133d0153fbc26f7507eaf8e99b2..3e27f8f015ed376fdd34e381ded6ffc48adb1db8 100644
--- a/webrtc/p2p/base/candidate.h
+++ b/webrtc/p2p/base/candidate.h
@@ -181,6 +181,13 @@ class Candidate {
            (related_address_ == c.related_address_);
   }
 
+  // Determines whether this candidate can be considered equivalent to the
+  // given one when looking for a matching candidate to remove.
+  bool MatchesForRemoval(const Candidate& c) const {
+    return component_ == c.component_ && protocol_ == c.protocol_ &&
+           address_ == c.address_;
+  }
+
   std::string ToString() const {
     return ToStringInternal(false);
   }