Late initialize MediaController, for less resource i.e. ProcessThread, usage by PeerConnection.

webrtc/api/webrtcsession.cc

 /*
  *  Copyright 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 630 matching lines @@
 
   return true;
 }
 
 void WebRtcSession::Close() {
   SetState(STATE_CLOSED);
   RemoveUnusedChannels(nullptr);
   ASSERT(!voice_channel_);
   ASSERT(!video_channel_);
   ASSERT(!data_channel_);
+  media_controller_->Close();
 }
 
 cricket::BaseChannel* WebRtcSession::GetChannel(
     const std::string& content_name) {
   if (voice_channel() && voice_channel()->content_name() == content_name) {
     return voice_channel();
   }
   if (video_channel() && video_channel()->content_name() == content_name) {
     return video_channel();
   }
@@ skipping 1449 matching lines @@
   }
 }
 
 void WebRtcSession::OnSentPacket_w(cricket::TransportChannel* channel,
                                    const rtc::SentPacket& sent_packet) {
   RTC_DCHECK(worker_thread()->IsCurrent());
   media_controller_->call_w()->OnSentPacket(sent_packet);
 }
 
 }  // namespace webrtc