Allow WebRtcMediaEngine to be created from any thread.

webrtc/media/base/fakemediaengine.h

 /*
  *  Copyright (c) 2004 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 757 matching lines @@
   FakeVoiceEngine(webrtc::AudioDeviceModule* adm,
                   const rtc::scoped_refptr<webrtc::AudioEncoderFactory>&
                       audio_encoder_factory,
                   const rtc::scoped_refptr<webrtc::AudioDecoderFactory>&
                       audio_decoder_factory,
                   rtc::scoped_refptr<webrtc::AudioMixer> audio_mixer) {
     // Add a fake audio codec. Note that the name must not be "" as there are
     // sanity checks against that.
     codecs_.push_back(AudioCodec(101, "fake_audio_codec", 0, 0, 1));
   }
+  void Init() {}
   rtc::scoped_refptr<webrtc::AudioState> GetAudioState() const {
     return rtc::scoped_refptr<webrtc::AudioState>();
   }
 
   VoiceMediaChannel* CreateChannel(webrtc::Call* call,
                                    const MediaConfig& config,
                                    const AudioOptions& options) {
     if (fail_create_channel_) {
       return nullptr;
     }
@@ skipping 178 matching lines @@
   virtual const std::vector<DataCodec>& data_codecs() { return data_codecs_; }
 
  private:
   std::vector<FakeDataMediaChannel*> channels_;
   std::vector<DataCodec> data_codecs_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_FAKEMEDIAENGINE_H_