Revert of Separating SCTP code from BaseChannel/MediaChannel.

webrtc/media/base/rtpdataengine.cc

Index: webrtc/media/base/rtpdataengine.cc
diff --git a/webrtc/media/base/rtpdataengine.cc b/webrtc/media/base/rtpdataengine.cc
index 96f5a3b95fc70d3edbde74fdb230779648b4170d..12a37fa180f59ed36f3ec2901aca3d2e1212a488 100644
--- a/webrtc/media/base/rtpdataengine.cc
+++ b/webrtc/media/base/rtpdataengine.cc
@@ -40,7 +40,11 @@ RtpDataEngine::RtpDataEngine() {
 }
 
 DataMediaChannel* RtpDataEngine::CreateChannel(
+    DataChannelType data_channel_type,
     const MediaConfig& config) {
+  if (data_channel_type != DCT_RTP) {
+    return NULL;
+  }
   return new RtpDataMediaChannel(config);
 }