Revert of Modify PeerConnection for end-to-end QuicDataChannel usage

webrtc/api/quicdatatransport.h

Index: webrtc/api/quicdatatransport.h
diff --git a/webrtc/api/quicdatatransport.h b/webrtc/api/quicdatatransport.h
index 96fe2a0ad73ebf2c56bdea41090ca53604f3df1f..f0c427d1b53dca52e936ca2b537d5b043dd6f623 100644
--- a/webrtc/api/quicdatatransport.h
+++ b/webrtc/api/quicdatatransport.h
@@ -36,9 +36,7 @@
 // exists, it sends the QUIC stream to the QuicDataChannel.
 class QuicDataTransport : public sigslot::has_slots<> {
  public:
-  QuicDataTransport(rtc::Thread* signaling_thread,
-                    rtc::Thread* worker_thread,
-                    rtc::Thread* network_thread);
+  QuicDataTransport(rtc::Thread* signaling_thread, rtc::Thread* worker_thread);
   ~QuicDataTransport() override;
 
   // Sets the QUIC transport channel for the QuicDataChannels and the
@@ -82,10 +80,9 @@
       quic_stream_by_id_;
   // QuicTransportChannel for sending/receiving data.
   cricket::QuicTransportChannel* quic_transport_channel_ = nullptr;
-  // Threads for the QUIC data channel.
+  // Signaling and worker threads for the QUIC data channel.
   rtc::Thread* const signaling_thread_;
   rtc::Thread* const worker_thread_;
-  rtc::Thread* const network_thread_;
 };
 
 }  // namespace webrtc