Revert of Adding the ability to create an RtpSender without a track.

talk/app/webrtc/peerconnectioninterface.h

Index: talk/app/webrtc/peerconnectioninterface.h
diff --git a/talk/app/webrtc/peerconnectioninterface.h b/talk/app/webrtc/peerconnectioninterface.h
index 317e6630525eb8aa696b65d653c01e0313c999c8..77caa9d78b2942bba82dcc7a863a1171ed503b7d 100644
--- a/talk/app/webrtc/peerconnectioninterface.h
+++ b/talk/app/webrtc/peerconnectioninterface.h
@@ -337,12 +337,6 @@
       AudioTrackInterface* track) = 0;
 
   // TODO(deadbeef): Make these pure virtual once all subclasses implement them.
-  // |kind| must be "audio" or "video".
-  virtual rtc::scoped_refptr<RtpSenderInterface> CreateSender(
-      const std::string& kind) {
-    return rtc::scoped_refptr<RtpSenderInterface>();
-  }
-
   virtual std::vector<rtc::scoped_refptr<RtpSenderInterface>> GetSenders()
       const {
     return std::vector<rtc::scoped_refptr<RtpSenderInterface>>();