Modified PeerConnection and WebRtcSession for end-to-end QuicDataChannel usage.

webrtc/api/peerconnectioninterface.h

Index: webrtc/api/peerconnectioninterface.h
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index e0eb1a46d49a4653d0893f945d97296262c625a6..fdf9cef51ec2a2a8b419227522d085a36b2c4ad2 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -296,6 +296,7 @@ class PeerConnectionInterface : public rtc::RefCountInterface {
     // default applies.
     bool disable_ipv6 = false;
     bool enable_rtp_data_channel = false;
+    bool enable_quic = false;
     rtc::Optional<int> screencast_min_bitrate;
     rtc::Optional<bool> combined_audio_video_bwe;
     rtc::Optional<bool> enable_dtls_srtp;