DataChannel[Interface]::[message/bytes]_[sent/received]() added.

webrtc/api/datachannelinterface.h

Index: webrtc/api/datachannelinterface.h
diff --git a/webrtc/api/datachannelinterface.h b/webrtc/api/datachannelinterface.h
index 53c11d4291a62965162519a75f1ec0bff1c9df13..8b788c04684a70368fa16d6fb113a3ed14e11ce8 100644
--- a/webrtc/api/datachannelinterface.h
+++ b/webrtc/api/datachannelinterface.h
@@ -125,6 +125,10 @@ class DataChannelInterface : public rtc::RefCountInterface {
 
   virtual int id() const = 0;
   virtual DataState state() const = 0;
+  virtual uint32_t messages_sent() const = 0;
+  virtual uint64_t bytes_sent() const = 0;
+  virtual uint32_t messages_received() const = 0;
+  virtual uint64_t bytes_received() const = 0;
   // The buffered_amount returns the number of bytes of application data
   // (UTF-8 text and binary data) that have been queued using SendBuffer but
   // have not yet been transmitted to the network.