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 ac7acabf057cdd06fa4beb915989bc49d65f04ec..7680a970a1593bebd1caf6c637b144627b91c33a 100644
--- a/webrtc/p2p/base/candidate.h
+++ b/webrtc/p2p/base/candidate.h
@@ -170,6 +170,13 @@ 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_;
+  }
+

[Taylor Brandstetter, 2016/02/10 21:58:08]

Why can't IsEquivalent be used?

[pthatcher1, 2016/02/11 20:25:51]

Because then we have to signal everything.  It would be nice to just have to
signal what's needed (the 3 tuple).

[Taylor Brandstetter, 2016/02/11 20:55:17]

Is there a reason why signaling the whole candidate is difficult?

[honghaiz3, 2016/02/12 00:56:55]

Signaling everything will consume unnecessary bandwidth. 
In theory, another option is to fill up the missing information like here:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/webrtc...
and then apply IsEquivalent. 
but I think adding a new method would require less computation. 
Do you think there is any case that protocco, address and component is the same
but other fields may be different so that we should treat the two candidates
differently?

   std::string ToString() const {
     return ToStringInternal(false);
   }