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

webrtc/api/statscollector.h

 /*
  *  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.
  */
 
 // This file contains a class used for gathering statistics from an ongoing
 // libjingle PeerConnection.
 
 #ifndef WEBRTC_API_STATSCOLLECTOR_H_
 #define WEBRTC_API_STATSCOLLECTOR_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/api/peerconnectioninterface.h"
 #include "webrtc/api/statstypes.h"
 #include "webrtc/api/webrtcsession.h"
+#include "webrtc/base/thread_checker.h"
 
 namespace webrtc {
 
 class PeerConnection;
 
 // Conversion function to convert candidate type string to the corresponding one
 // from  enum RTCStatsIceCandidateType.
 const char* IceCandidateTypeToStatsType(const std::string& candidate_type);
 
 // Conversion function to convert adapter type to report string which are more
@@ skipping 90 matching lines @@
 
   // Helper method to get the id for the track identified by ssrc.
   // |direction| tells if the track is for sending or receiving.
   bool GetTrackIdBySsrc(uint32_t ssrc,
                         std::string* track_id,
                         StatsReport::Direction direction);
 
   // Helper method to update the timestamp of track records.
   void UpdateTrackReports();
 
+  rtc::ThreadChecker signal_thread_checker_;
+
   // A collection for all of our stats reports.
   StatsCollection reports_;
   TrackIdMap track_ids_;
   // Raw pointer to the peer connection the statistics are gathered from.
   PeerConnection* const pc_;
   double stats_gathering_started_;
   ProxyTransportMap proxy_to_transport_;
 
   // TODO(tommi): We appear to be holding on to raw pointers to reference
   // counted objects?  We should be using scoped_refptr here.
   typedef std::vector<std::pair<AudioTrackInterface*, uint32_t> >
       LocalAudioTrackVector;
   LocalAudioTrackVector local_audio_tracks_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_STATSCOLLECTOR_H_