Ping the premier connection on each network with higher priority.

webrtc/p2p/base/p2ptransportchannel.h

Index: webrtc/p2p/base/p2ptransportchannel.h
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index 672abb7423b95f1904428c0a8873d4e6c6262c32..637708262c7cd9b701f43693699cad98d1714c3d 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -43,8 +43,8 @@ namespace cricket {
 enum class IceRestartState { CONNECTING, CONNECTED, DISCONNECTED, MAX_VALUE };
 
 extern const int WEAK_PING_INTERVAL;
-extern const int STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL;
-extern const int STABLE_WRITABLE_CONNECTION_PING_INTERVAL;
+extern const int WEAK_OR_STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL;
+extern const int STRONG_AND_STABLE_WRITABLE_CONNECTION_PING_INTERVAL;
 static const int MIN_PINGS_AT_WEAK_PING_INTERVAL = 3;
 
 // Adds the port on which the candidate originated.
@@ -261,7 +261,9 @@ class P2PTransportChannel : public TransportChannelImpl,
   void RememberRemoteCandidate(const Candidate& remote_candidate,
                                PortInterface* origin_port);
   bool IsPingable(const Connection* conn, int64_t now) const;
-  bool IsSelectedConnectionPingable(int64_t now);
+  // Whether a premier connection is pingable, where a premier connection is
+  // the top-ranked connection on each network.
+  bool IsPremierConnectionPingable(Connection* premier_conn, int64_t now);
   int CalculateActiveWritablePingInterval(const Connection* conn,
                                           int64_t now) const;
   void PingConnection(Connection* conn);
@@ -317,12 +319,15 @@ class P2PTransportChannel : public TransportChannelImpl,
   // Returns true if the new_connection is selected for transmission.
   bool MaybeSwitchSelectedConnection(Connection* new_connection,
                                      const std::string& reason);
-
+  // Gets all premier connections on all networks.
+  std::map<rtc::Network*, Connection*> GetPremierConnectionsByNetwork() const;
   void PruneConnections();
   bool IsBackupConnection(const Connection* conn) const;
 
   Connection* FindConnectionToPing(int64_t now);
   Connection* FindOldestConnectionNeedingTriggeredCheck(int64_t now);
+  // Finds the best premier connection for pinging.

[pthatcher1, 2016/10/24 20:49:05]

I find this confusing since "best" and "premier" almost mean the same thing. 
What we actually have here is a "best per network" and "best across networks".

Can we have "best" mean "best across networks" and "best for network" mean "best
per network"?  For example, this method could just be
"FindBestConnectionToPing"?  And the method above could be
GetBestConnectionForNetwork(). 

[honghaiz3, 2016/10/24 23:35:09]

Removed this method base on another suggestion. 

+  Connection* FindBestPremierConnectionToPing(int64_t now);
   // Between |conn1| and |conn2|, this function returns the one which should
   // be pinged first.
   Connection* SelectMostPingableConnection(Connection* conn1,