Remove BaseSession::SignalNewDescription. It was only used by GTP and now just clutters the code.

talk/app/webrtc/webrtcsession.h

Index: talk/app/webrtc/webrtcsession.h
diff --git a/talk/app/webrtc/webrtcsession.h b/talk/app/webrtc/webrtcsession.h
index a2cba209703068437ea7728995f1196499d45c09..30ebc1e49ee8dcc07e015e20f784f87d84af725e 100644
--- a/talk/app/webrtc/webrtcsession.h
+++ b/talk/app/webrtc/webrtcsession.h
@@ -258,19 +258,6 @@ class WebRtcSession : public cricket::BaseSession,
     metrics_observer_ = metrics_observer;
   }
 
- protected:
-  // Don't fire a new description.  The only thing it's used for is to
-  // push new media descriptions to the BaseChannels.  But in
-  // WebRtcSession, we just push to the BaseChannels directly, so we
-  // don't need this (and it would cause the descriptions to be pushed
-  // down twice).
-  // TODO(pthatcher): Remove this method and signal completely from
-  // BaseSession once all the subclasses of BaseSession push to
-  // BaseChannels directly rather than relying on the signal, or once
-  // BaseChannel no longer listens to the event and requires
-  // descriptions to be pushed down.
-  virtual void SignalNewDescription() override {}
-
  private:
   // Indicates the type of SessionDescription in a call to SetLocalDescription
   // and SetRemoteDescription.