Dampening connection switch.

webrtc/p2p/base/port.h

Index: webrtc/p2p/base/port.h
diff --git a/webrtc/p2p/base/port.h b/webrtc/p2p/base/port.h
index 2c3b61b718307173d152a1c8f35ecf933b00aaed..190a374ce62f00c1a3a14910e75d79369cc8fc28 100644
--- a/webrtc/p2p/base/port.h
+++ b/webrtc/p2p/base/port.h
@@ -590,6 +590,17 @@ class Connection : public CandidatePairInterface,
   // Returns the last received time of any data, stun request, or stun
   // response in milliseconds
   int64_t last_received() const;
+  // Returns the first time since which the connection has been in receiving
+  // state.

[pthatcher1, 2016/07/14 18:01:44]

I think it should be more like the time at which we transitioned from not
receiving -> receiving and haven't transitioned to not receiving since.

[honghaiz3, 2016/07/14 23:15:01]

Done.

+  int64_t continuously_receiving_since() const {
+    return continuously_receiving_since_;
+  }
+
+  void reset_continuously_receiving_since(int64_t now) {
+    if (continuously_receiving_since_ > 0) {
+      continuously_receiving_since_ = now;
+    }
+  }
 
   bool stable(int64_t now) const;
 
@@ -618,7 +629,7 @@ class Connection : public CandidatePairInterface,
 
   // Changes the state and signals if necessary.
   void set_write_state(WriteState value);
-  void set_receiving(bool value);
+  void UpdateReceiving(int64_t now);
   void set_state(State state);
   void set_connected(bool value);
 
@@ -648,6 +659,7 @@ class Connection : public CandidatePairInterface,
                                 // side
   int64_t last_data_received_;
   int64_t last_ping_response_received_;
+  int64_t continuously_receiving_since_ = 0;

[pthatcher1, 2016/07/14 18:01:44]

Well, that makes it sounds like we've been continuously receiving forever. 
Perhaps using an rtc::optional would be more careful not to get confused about
that.  Or make it 7FFF FFFF.

[honghaiz3, 2016/07/14 23:15:01]

As I said, the value should not be used at all if the connection is not in
receiving state. So it does not matter what value we put there and it does not
worth using an optional here. 
What about -1?

   std::vector<SentPing> pings_since_last_response_;
 
   rtc::RateTracker recv_rate_tracker_;