Remove event_channel() and control_channel() from Session interface.

remoting/protocol/rtp_video_writer.cc

Index: remoting/protocol/rtp_video_writer.cc
diff --git a/remoting/protocol/rtp_video_writer.cc b/remoting/protocol/rtp_video_writer.cc
index 7d83d06fe72eac34ed4d31e644faa998fff2aee4..f6bcb643fdc09163b153c926cf9de578d32270be 100644
--- a/remoting/protocol/rtp_video_writer.cc
+++ b/remoting/protocol/rtp_video_writer.cc
@@ -81,6 +81,10 @@ void RtpVideoWriter::Close() {
   }
 }
 
+bool RtpVideoWriter::is_connected() {
+  return rtp_channel_.get() && rtcp_channel_.get();
+}
+
 void RtpVideoWriter::ProcessVideoPacket(const VideoPacket* packet,
                                         const base::Closure& done) {
   CHECK(packet->format().encoding() == VideoPacketFormat::ENCODING_VP8)