Added network thread to rtc::BaseChannel

webrtc/pc/channel.h

 /*
  *  Copyright 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.
  */
 
 #ifndef WEBRTC_PC_CHANNEL_H_
 #define WEBRTC_PC_CHANNEL_H_
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "webrtc/audio_sink.h"
+#include "webrtc/base/asyncinvoker.h"
 #include "webrtc/base/asyncudpsocket.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/network.h"
 #include "webrtc/base/sigslot.h"
 #include "webrtc/base/window.h"
 #include "webrtc/media/base/mediachannel.h"
 #include "webrtc/media/base/mediaengine.h"
 #include "webrtc/media/base/streamparams.h"
 #include "webrtc/media/base/videosinkinterface.h"
 #include "webrtc/media/base/videosourceinterface.h"
 #include "webrtc/p2p/base/transportcontroller.h"
 #include "webrtc/p2p/client/socketmonitor.h"
 #include "webrtc/pc/audiomonitor.h"
 #include "webrtc/pc/bundlefilter.h"
 #include "webrtc/pc/mediamonitor.h"
 #include "webrtc/pc/mediasession.h"
 #include "webrtc/pc/rtcpmuxfilter.h"
 #include "webrtc/pc/srtpfilter.h"
 
 namespace webrtc {
 class AudioSinkInterface;
 }  // namespace webrtc
 
 namespace cricket {
 
 struct CryptoParams;
 class MediaContentDescription;
 
-enum SinkType {
-  SINK_PRE_CRYPTO,  // Sink packets before encryption or after decryption.
-  SINK_POST_CRYPTO  // Sink packets after encryption or before decryption.
-};
-
 // BaseChannel contains logic common to voice and video, including
-// enable, marshaling calls to a worker thread, and
+// enable, marshaling calls to a worker and network threads, and
 // connection and media monitors.
+// BaseChannel assumes signaling and other threads allowed to make synchronius

[stefan-webrtc, 2016/05/11 13:10:26]

"...are allowed to make synchronous calls to the worker thread, the worker
thread makes synchronous calls only to the network thread, and the network
thread can't be blocked by other threads."

[danilchap, 2016/05/11 14:15:30]

Thank you!

+// calls to worker thread, worker thread make synchronius calls only
+// to network thread, and network thread can't be blocked by other threads.
+// All methods with _n suffix must be called on network thread,
+//     methods with _w suffix - on worker thread
+// and methods with _s suffix on signaling thread.
+// Network and worker threads may be the same thread.
 //
 // WARNING! SUBCLASSES MUST CALL Deinit() IN THEIR DESTRUCTORS!
 // This is required to avoid a data race between the destructor modifying the
 // vtable, and the media channel's thread using BaseChannel as the
 // NetworkInterface.
 
 class BaseChannel
     : public rtc::MessageHandler, public sigslot::has_slots<>,
       public MediaChannel::NetworkInterface,
       public ConnectionStatsGetter {
  public:
-  BaseChannel(rtc::Thread* thread,
+  BaseChannel(rtc::Thread* worker_thread,
+              rtc::Thread* network_thread,
               MediaChannel* channel,
               TransportController* transport_controller,
               const std::string& content_name,
               bool rtcp);
   virtual ~BaseChannel();
-  bool Init();
-  // Deinit may be called multiple times and is simply ignored if it's alreay
+  bool Init_w();
+  // Deinit may be called multiple times and is simply ignored if it's already
   // done.
   void Deinit();
 
   rtc::Thread* worker_thread() const { return worker_thread_; }
+  rtc::Thread* network_thread() const { return network_thread_; }
   const std::string& content_name() const { return content_name_; }
   const std::string& transport_name() const { return transport_name_; }
-  TransportChannel* transport_channel() const {
-    return transport_channel_;
-  }
-  TransportChannel* rtcp_transport_channel() const {
-    return rtcp_transport_channel_;
-  }
   bool enabled() const { return enabled_; }
 
   // This function returns true if we are using SRTP.
   bool secure() const { return srtp_filter_.IsActive(); }
   // The following function returns true if we are using
   // DTLS-based keying. If you turned off SRTP later, however
   // you could have secure() == false and dtls_secure() == true.
   bool secure_dtls() const { return dtls_keyed_; }
   // This function returns true if we require secure channel for call setup.
   bool secure_required() const { return secure_required_; }
@@ skipping 37 matching lines @@
   BundleFilter* bundle_filter() { return &bundle_filter_; }
 
   const std::vector<StreamParams>& local_streams() const {
     return local_streams_;
   }
   const std::vector<StreamParams>& remote_streams() const {
     return remote_streams_;
   }
 
   sigslot::signal2<BaseChannel*, bool> SignalDtlsSetupFailure;
-  void SignalDtlsSetupFailure_w(bool rtcp);
+  void SignalDtlsSetupFailure_n(bool rtcp);
   void SignalDtlsSetupFailure_s(bool rtcp);
 
   // Used for latency measurements.
   sigslot::signal1<BaseChannel*> SignalFirstPacketReceived;
 
+  // Forward TransportChannel SignalSentPacket to worker thread.
+  sigslot::signal1<const rtc::SentPacket&> SignalSentPacket;
+
+  // Only public for unit tests.  Otherwise, consider private.
+  TransportChannel* transport_channel() const { return transport_channel_; }
+  TransportChannel* rtcp_transport_channel() const {
+    return rtcp_transport_channel_;
+  }
+
   // Made public for easier testing.
   void SetReadyToSend(bool rtcp, bool ready);
 
   // Only public for unit tests.  Otherwise, consider protected.
   int SetOption(SocketType type, rtc::Socket::Option o, int val)
       override;
+  int SetOption_n(SocketType type, rtc::Socket::Option o, int val);
 
   SrtpFilter* srtp_filter() { return &srtp_filter_; }
 
  protected:
   virtual MediaChannel* media_channel() const { return media_channel_; }
   // Sets the |transport_channel_| (and |rtcp_transport_channel_|, if |rtcp_| is
   // true). Gets the transport channels from |transport_controller_|.
-  bool SetTransport_w(const std::string& transport_name);
+  bool SetTransport_n(const std::string& transport_name);
 
-  void set_transport_channel(TransportChannel* transport);
-  void set_rtcp_transport_channel(TransportChannel* transport,
-                                  bool update_writablity);
+  void SetTransportChannel_n(TransportChannel* transport);
+  void SetRtcpTransportChannel_n(TransportChannel* transport,
+                                 bool update_writablity);
 
   bool was_ever_writable() const { return was_ever_writable_; }
   void set_local_content_direction(MediaContentDirection direction) {
     local_content_direction_ = direction;
   }
   void set_remote_content_direction(MediaContentDirection direction) {
     remote_content_direction_ = direction;
   }
   void set_secure_required(bool secure_required) {
     secure_required_ = secure_required;
   }
-  bool IsReadyToReceive() const;
-  bool IsReadyToSend() const;
+  bool IsReadyToReceive_w() const;
+  bool IsReadyToSend_w() const;
   rtc::Thread* signaling_thread() {
     return transport_controller_->signaling_thread();
   }
   bool rtcp_transport_enabled() const { return rtcp_transport_enabled_; }
 
   void ConnectToTransportChannel(TransportChannel* tc);
   void DisconnectFromTransportChannel(TransportChannel* tc);
 
-  void FlushRtcpMessages();
+  void FlushRtcpMessages_n();
 
   // NetworkInterface implementation, called by MediaEngine
   bool SendPacket(rtc::CopyOnWriteBuffer* packet,
                   const rtc::PacketOptions& options) override;
   bool SendRtcp(rtc::CopyOnWriteBuffer* packet,
                 const rtc::PacketOptions& options) override;
 
   // From TransportChannel
   void OnWritableState(TransportChannel* channel);
   virtual void OnChannelRead(TransportChannel* channel,
                              const char* data,
                              size_t len,
                              const rtc::PacketTime& packet_time,
                              int flags);
   void OnReadyToSend(TransportChannel* channel);
 
   void OnDtlsState(TransportChannel* channel, DtlsTransportState state);
 
   void OnSelectedCandidatePairChanged(
       TransportChannel* channel,
       CandidatePairInterface* selected_candidate_pair,
       int last_sent_packet_id);
 
   bool PacketIsRtcp(const TransportChannel* channel, const char* data,
                     size_t len);
   bool SendPacket(bool rtcp,
                   rtc::CopyOnWriteBuffer* packet,
                   const rtc::PacketOptions& options);
+
   virtual bool WantsPacket(bool rtcp, const rtc::CopyOnWriteBuffer* packet);
   void HandlePacket(bool rtcp, rtc::CopyOnWriteBuffer* packet,
                     const rtc::PacketTime& packet_time);
+  void OnPacketReceived(bool rtcp,
+                        const rtc::CopyOnWriteBuffer& packet,
+                        const rtc::PacketTime& packet_time);
 
   void EnableMedia_w();
   void DisableMedia_w();
-  void UpdateWritableState_w();
-  void ChannelWritable_w();
-  void ChannelNotWritable_w();
+  void UpdateWritableState_n();
+  void ChannelWritable_n();
+  void ChannelNotWritable_n();
   bool AddRecvStream_w(const StreamParams& sp);
   bool RemoveRecvStream_w(uint32_t ssrc);
   bool AddSendStream_w(const StreamParams& sp);
   bool RemoveSendStream_w(uint32_t ssrc);
-  virtual bool ShouldSetupDtlsSrtp() const;
+  virtual bool ShouldSetupDtlsSrtp_n() const;
   // Do the DTLS key expansion and impose it on the SRTP/SRTCP filters.
   // |rtcp_channel| indicates whether to set up the RTP or RTCP filter.
-  bool SetupDtlsSrtp(bool rtcp_channel);
-  void MaybeSetupDtlsSrtp_w();
+  bool SetupDtlsSrtp_n(bool rtcp_channel);
+  void MaybeSetupDtlsSrtp_n();
   // Set the DTLS-SRTP cipher policy on this channel as appropriate.
-  bool SetDtlsSrtpCryptoSuites(TransportChannel* tc, bool rtcp);
+  bool SetDtlsSrtpCryptoSuites_n(TransportChannel* tc, bool rtcp);
 
-  virtual void ChangeState() = 0;
+  void ChangeState();
+  virtual void ChangeState_w() = 0;
 
   // Gets the content info appropriate to the channel (audio or video).
   virtual const ContentInfo* GetFirstContent(
       const SessionDescription* sdesc) = 0;
   bool UpdateLocalStreams_w(const std::vector<StreamParams>& streams,
                             ContentAction action,
                             std::string* error_desc);
   bool UpdateRemoteStreams_w(const std::vector<StreamParams>& streams,
                              ContentAction action,
                              std::string* error_desc);
   virtual bool SetLocalContent_w(const MediaContentDescription* content,
                                  ContentAction action,
                                  std::string* error_desc) = 0;
   virtual bool SetRemoteContent_w(const MediaContentDescription* content,
                                   ContentAction action,
                                   std::string* error_desc) = 0;
-  bool SetRtpTransportParameters_w(const MediaContentDescription* content,
+  bool SetRtpTransportParameters(const MediaContentDescription* content,
+                                 ContentAction action,
+                                 ContentSource src,
+                                 std::string* error_desc);
+  bool SetRtpTransportParameters_n(const MediaContentDescription* content,
                                    ContentAction action,
                                    ContentSource src,
                                    std::string* error_desc);
 
   // Helper method to get RTP Absoulute SendTime extension header id if
   // present in remote supported extensions list.
-  void MaybeCacheRtpAbsSendTimeHeaderExtension(
+  void MaybeCacheRtpAbsSendTimeHeaderExtension_w(
       const std::vector<RtpHeaderExtension>& extensions);
 
-  bool CheckSrtpConfig(const std::vector<CryptoParams>& cryptos,
-                       bool* dtls,
-                       std::string* error_desc);
-  bool SetSrtp_w(const std::vector<CryptoParams>& params,
+  bool CheckSrtpConfig_n(const std::vector<CryptoParams>& cryptos,
+                         bool* dtls,
+                         std::string* error_desc);
+  bool SetSrtp_n(const std::vector<CryptoParams>& params,
                  ContentAction action,
                  ContentSource src,
                  std::string* error_desc);
-  void ActivateRtcpMux_w();
-  bool SetRtcpMux_w(bool enable,
+  void ActivateRtcpMux_n();
+  bool SetRtcpMux_n(bool enable,
                     ContentAction action,
                     ContentSource src,
                     std::string* error_desc);
 
   // From MessageHandler
   void OnMessage(rtc::Message* pmsg) override;
 
   // Handled in derived classes
   // Get the SRTP crypto suites to use for RTP media
-  virtual void GetSrtpCryptoSuites(std::vector<int>* crypto_suites) const = 0;
+  virtual void GetSrtpCryptoSuites_n(std::vector<int>* crypto_suites) const = 0;
   virtual void OnConnectionMonitorUpdate(ConnectionMonitor* monitor,
       const std::vector<ConnectionInfo>& infos) = 0;
 
   // Helper function for invoking bool-returning methods on the worker thread.
   template <class FunctorT>
   bool InvokeOnWorker(const FunctorT& functor) {
     return worker_thread_->Invoke<bool>(functor);
   }
 
  private:
-  rtc::Thread* worker_thread_;
-  TransportController* transport_controller_;
-  MediaChannel* media_channel_;
-  std::vector<StreamParams> local_streams_;
-  std::vector<StreamParams> remote_streams_;
+  bool InitNetwork_n();
+  void DeinitNetwork_n();
+  void SignalSentPacket_n(TransportChannel* channel,
+                          const rtc::SentPacket& sent_packet);
+  void SignalSentPacket_w(const rtc::SentPacket& sent_packet);
+  bool IsTransportReadyToSend_n() const;
+  void CacheRtpAbsSendTimeHeaderExtension_n(int rtp_abs_sendtime_extn_id);
+
+  rtc::Thread* const worker_thread_;
+  rtc::Thread* const network_thread_;
+  rtc::AsyncInvoker invoker_;
 
   const std::string content_name_;
+  std::unique_ptr<ConnectionMonitor> connection_monitor_;
+
+  // Transport related members that should be accessed from network thread.
+  TransportController* const transport_controller_;
   std::string transport_name_;
   bool rtcp_transport_enabled_;
   TransportChannel* transport_channel_;
   std::vector<std::pair<rtc::Socket::Option, int> > socket_options_;
   TransportChannel* rtcp_transport_channel_;
   std::vector<std::pair<rtc::Socket::Option, int> > rtcp_socket_options_;
   SrtpFilter srtp_filter_;
   RtcpMuxFilter rtcp_mux_filter_;
   BundleFilter bundle_filter_;
-  std::unique_ptr<ConnectionMonitor> connection_monitor_;
-  bool enabled_;
-  bool writable_;
   bool rtp_ready_to_send_;
   bool rtcp_ready_to_send_;
+  bool writable_;
   bool was_ever_writable_;
-  MediaContentDirection local_content_direction_;
-  MediaContentDirection remote_content_direction_;
   bool has_received_packet_;
   bool dtls_keyed_;
   bool secure_required_;
   int rtp_abs_sendtime_extn_id_;
+
+  // MediaChannel related members that should be access from worker thread.
+  MediaChannel* const media_channel_;
+  // Currently enabled_ flag accessed from signaling thread too, but it can
+  // be changed only when signaling thread does sunchronious call to worker
+  // thread, so it should be safe.
+  bool enabled_;
+  std::vector<StreamParams> local_streams_;
+  std::vector<StreamParams> remote_streams_;
+  MediaContentDirection local_content_direction_;
+  MediaContentDirection remote_content_direction_;
 };
 
 // VoiceChannel is a specialization that adds support for early media, DTMF,
 // and input/output level monitoring.
 class VoiceChannel : public BaseChannel {
  public:
-  VoiceChannel(rtc::Thread* thread,
+  VoiceChannel(rtc::Thread* worker_thread,
+               rtc::Thread* network_thread,
                MediaEngineInterface* media_engine,
                VoiceMediaChannel* channel,
                TransportController* transport_controller,
                const std::string& content_name,
                bool rtcp);
   ~VoiceChannel();
-  bool Init();
+  bool Init_w();
 
   // Configure sending media on the stream with SSRC |ssrc|
   // If there is only one sending stream SSRC 0 can be used.
   bool SetAudioSend(uint32_t ssrc,
                     bool enable,
                     const AudioOptions* options,
                     AudioSource* source);
 
   // downcasts a MediaChannel
-  virtual VoiceMediaChannel* media_channel() const {
+  VoiceMediaChannel* media_channel() const override {
     return static_cast<VoiceMediaChannel*>(BaseChannel::media_channel());
   }
 
   void SetEarlyMedia(bool enable);
   // This signal is emitted when we have gone a period of time without
   // receiving early media. When received, a UI should start playing its
   // own ringing sound
   sigslot::signal1<VoiceChannel*> SignalEarlyMediaTimeout;
 
   // Returns if the telephone-event has been negotiated.
@@ skipping 27 matching lines @@
   sigslot::signal2<VoiceChannel*, const AudioInfo&> SignalAudioMonitor;
 
   int GetInputLevel_w();
   int GetOutputLevel_w();
   void GetActiveStreams_w(AudioInfo::StreamList* actives);
   webrtc::RtpParameters GetRtpParameters_w(uint32_t ssrc) const;
   bool SetRtpParameters_w(uint32_t ssrc, webrtc::RtpParameters parameters);
 
  private:
   // overrides from BaseChannel
-  virtual void OnChannelRead(TransportChannel* channel,
-                             const char* data, size_t len,
-                             const rtc::PacketTime& packet_time,
-                             int flags);
-  virtual void ChangeState();
-  virtual const ContentInfo* GetFirstContent(const SessionDescription* sdesc);
-  virtual bool SetLocalContent_w(const MediaContentDescription* content,
-                                 ContentAction action,
-                                 std::string* error_desc);
-  virtual bool SetRemoteContent_w(const MediaContentDescription* content,
-                                  ContentAction action,
-                                  std::string* error_desc);
+  void OnChannelRead(TransportChannel* channel,
+                     const char* data,
+                     size_t len,
+                     const rtc::PacketTime& packet_time,
+                     int flags) override;
+  void ChangeState_w() override;
+  const ContentInfo* GetFirstContent(const SessionDescription* sdesc) override;
+  bool SetLocalContent_w(const MediaContentDescription* content,
+                         ContentAction action,
+                         std::string* error_desc) override;
+  bool SetRemoteContent_w(const MediaContentDescription* content,
+                          ContentAction action,
+                          std::string* error_desc) override;
   void HandleEarlyMediaTimeout();
   bool InsertDtmf_w(uint32_t ssrc, int event, int duration);
   bool SetOutputVolume_w(uint32_t ssrc, double volume);
   bool GetStats_w(VoiceMediaInfo* stats);
 
-  virtual void OnMessage(rtc::Message* pmsg);
-  virtual void GetSrtpCryptoSuites(std::vector<int>* crypto_suites) const;
-  virtual void OnConnectionMonitorUpdate(
-      ConnectionMonitor* monitor, const std::vector<ConnectionInfo>& infos);
-  virtual void OnMediaMonitorUpdate(
-      VoiceMediaChannel* media_channel, const VoiceMediaInfo& info);
+  void OnMessage(rtc::Message* pmsg) override;
+  void GetSrtpCryptoSuites_n(std::vector<int>* crypto_suites) const override;
+  void OnConnectionMonitorUpdate(
+      ConnectionMonitor* monitor,
+      const std::vector<ConnectionInfo>& infos) override;
+  void OnMediaMonitorUpdate(VoiceMediaChannel* media_channel,
+                            const VoiceMediaInfo& info);
   void OnAudioMonitorUpdate(AudioMonitor* monitor, const AudioInfo& info);
 
   static const int kEarlyMediaTimeout = 1000;
   MediaEngineInterface* media_engine_;
   bool received_media_;
   std::unique_ptr<VoiceMediaMonitor> media_monitor_;
   std::unique_ptr<AudioMonitor> audio_monitor_;
 
   // Last AudioSendParameters sent down to the media_channel() via
   // SetSendParameters.
   AudioSendParameters last_send_params_;
   // Last AudioRecvParameters sent down to the media_channel() via
   // SetRecvParameters.
   AudioRecvParameters last_recv_params_;
 };
 
 // VideoChannel is a specialization for video.
 class VideoChannel : public BaseChannel {
  public:
-  VideoChannel(rtc::Thread* thread,
+  VideoChannel(rtc::Thread* worker_thread,
+               rtc::Thread* netwokr_thread,
                VideoMediaChannel* channel,
                TransportController* transport_controller,
                const std::string& content_name,
                bool rtcp);
   ~VideoChannel();
-  bool Init();
+  bool Init_w();
 
   // downcasts a MediaChannel
-  virtual VideoMediaChannel* media_channel() const {
+  VideoMediaChannel* media_channel() const override {
     return static_cast<VideoMediaChannel*>(BaseChannel::media_channel());
   }
 
   bool SetSink(uint32_t ssrc, rtc::VideoSinkInterface<VideoFrame>* sink);
   // Register a source. The |ssrc| must correspond to a registered
   // send stream.
   void SetSource(uint32_t ssrc,
                  rtc::VideoSourceInterface<cricket::VideoFrame>* source);
   // Get statistics about the current media session.
   bool GetStats(VideoMediaInfo* stats);
 
   sigslot::signal2<VideoChannel*, const std::vector<ConnectionInfo>&>
       SignalConnectionMonitor;
 
   void StartMediaMonitor(int cms);
   void StopMediaMonitor();
   sigslot::signal2<VideoChannel*, const VideoMediaInfo&> SignalMediaMonitor;
 
   bool SetVideoSend(uint32_t ssrc, bool enable, const VideoOptions* options);
   webrtc::RtpParameters GetRtpParameters(uint32_t ssrc) const;
   bool SetRtpParameters(uint32_t ssrc, const webrtc::RtpParameters& parameters);
 
  private:
   // overrides from BaseChannel
-  virtual void ChangeState();
-  virtual const ContentInfo* GetFirstContent(const SessionDescription* sdesc);
-  virtual bool SetLocalContent_w(const MediaContentDescription* content,
-                                 ContentAction action,
-                                 std::string* error_desc);
-  virtual bool SetRemoteContent_w(const MediaContentDescription* content,
-                                  ContentAction action,
-                                  std::string* error_desc);
+  void ChangeState_w() override;
+  const ContentInfo* GetFirstContent(const SessionDescription* sdesc) override;
+  bool SetLocalContent_w(const MediaContentDescription* content,
+                         ContentAction action,
+                         std::string* error_desc) override;
+  bool SetRemoteContent_w(const MediaContentDescription* content,
+                          ContentAction action,
+                          std::string* error_desc) override;
   bool GetStats_w(VideoMediaInfo* stats);
   webrtc::RtpParameters GetRtpParameters_w(uint32_t ssrc) const;
   bool SetRtpParameters_w(uint32_t ssrc, webrtc::RtpParameters parameters);
 
-  virtual void OnMessage(rtc::Message* pmsg);
-  virtual void GetSrtpCryptoSuites(std::vector<int>* crypto_suites) const;
-  virtual void OnConnectionMonitorUpdate(
-      ConnectionMonitor* monitor, const std::vector<ConnectionInfo>& infos);
-  virtual void OnMediaMonitorUpdate(
-      VideoMediaChannel* media_channel, const VideoMediaInfo& info);
+  void OnMessage(rtc::Message* pmsg) override;
+  void GetSrtpCryptoSuites_n(std::vector<int>* crypto_suites) const override;
+  void OnConnectionMonitorUpdate(
+      ConnectionMonitor* monitor,
+      const std::vector<ConnectionInfo>& infos) override;
+  void OnMediaMonitorUpdate(VideoMediaChannel* media_channel,
+                            const VideoMediaInfo& info);
 
   std::unique_ptr<VideoMediaMonitor> media_monitor_;
 
   // Last VideoSendParameters sent down to the media_channel() via
   // SetSendParameters.
   VideoSendParameters last_send_params_;
   // Last VideoRecvParameters sent down to the media_channel() via
   // SetRecvParameters.
   VideoRecvParameters last_recv_params_;
 };
 
 // DataChannel is a specialization for data.
 class DataChannel : public BaseChannel {
  public:
-  DataChannel(rtc::Thread* thread,
+  DataChannel(rtc::Thread* worker_thread,
+              rtc::Thread* network_thread,
               DataMediaChannel* media_channel,
               TransportController* transport_controller,
               const std::string& content_name,
               bool rtcp);
   ~DataChannel();
-  bool Init();
+  bool Init_w();
 
   virtual bool SendData(const SendDataParams& params,
                         const rtc::CopyOnWriteBuffer& payload,
                         SendDataResult* result);
 
   void StartMediaMonitor(int cms);
   void StopMediaMonitor();
 
   // Should be called on the signaling thread only.
   bool ready_to_send_data() const {
     return ready_to_send_data_;
   }
 
   sigslot::signal2<DataChannel*, const DataMediaInfo&> SignalMediaMonitor;
   sigslot::signal2<DataChannel*, const std::vector<ConnectionInfo>&>
       SignalConnectionMonitor;
   sigslot::signal3<DataChannel*, const ReceiveDataParams&,
       const rtc::CopyOnWriteBuffer&> SignalDataReceived;
   // Signal for notifying when the channel becomes ready to send data.
   // That occurs when the channel is enabled, the transport is writable,
   // both local and remote descriptions are set, and the channel is unblocked.
   sigslot::signal1<bool> SignalReadyToSendData;
   // Signal for notifying that the remote side has closed the DataChannel.
   sigslot::signal1<uint32_t> SignalStreamClosedRemotely;
 
  protected:
   // downcasts a MediaChannel.
-  virtual DataMediaChannel* media_channel() const {
+  DataMediaChannel* media_channel() const override {
     return static_cast<DataMediaChannel*>(BaseChannel::media_channel());
   }
 
  private:
   struct SendDataMessageData : public rtc::MessageData {
     SendDataMessageData(const SendDataParams& params,
                         const rtc::CopyOnWriteBuffer* payload,
                         SendDataResult* result)
         : params(params),
           payload(payload),
@@ skipping 16 matching lines @@
         : params(params),
           payload(data, len) {
     }
     const ReceiveDataParams params;
     const rtc::CopyOnWriteBuffer payload;
   };
 
   typedef rtc::TypedMessageData<bool> DataChannelReadyToSendMessageData;
 
   // overrides from BaseChannel
-  virtual const ContentInfo* GetFirstContent(const SessionDescription* sdesc);
+  const ContentInfo* GetFirstContent(const SessionDescription* sdesc) override;
   // If data_channel_type_ is DCT_NONE, set it.  Otherwise, check that
   // it's the same as what was set previously.  Returns false if it's
   // set to one type one type and changed to another type later.
   bool SetDataChannelType(DataChannelType new_data_channel_type,
                           std::string* error_desc);
   // Same as SetDataChannelType, but extracts the type from the
   // DataContentDescription.
   bool SetDataChannelTypeFromContent(const DataContentDescription* content,
                                      std::string* error_desc);
-  virtual bool SetLocalContent_w(const MediaContentDescription* content,
-                                 ContentAction action,
-                                 std::string* error_desc);
-  virtual bool SetRemoteContent_w(const MediaContentDescription* content,
-                                  ContentAction action,
-                                  std::string* error_desc);
-  virtual void ChangeState();
-  virtual bool WantsPacket(bool rtcp, const rtc::CopyOnWriteBuffer* packet);
+  bool SetLocalContent_w(const MediaContentDescription* content,
+                         ContentAction action,
+                         std::string* error_desc) override;
+  bool SetRemoteContent_w(const MediaContentDescription* content,
+                          ContentAction action,
+                          std::string* error_desc) override;
+  void ChangeState_w() override;
+  bool WantsPacket(bool rtcp, const rtc::CopyOnWriteBuffer* packet) override;
 
-  virtual void OnMessage(rtc::Message* pmsg);
-  virtual void GetSrtpCryptoSuites(std::vector<int>* crypto_suites) const;
-  virtual void OnConnectionMonitorUpdate(
-      ConnectionMonitor* monitor, const std::vector<ConnectionInfo>& infos);
-  virtual void OnMediaMonitorUpdate(
-      DataMediaChannel* media_channel, const DataMediaInfo& info);
-  virtual bool ShouldSetupDtlsSrtp() const;
+  void OnMessage(rtc::Message* pmsg) override;
+  void GetSrtpCryptoSuites_n(std::vector<int>* crypto_suites) const override;
+  void OnConnectionMonitorUpdate(
+      ConnectionMonitor* monitor,
+      const std::vector<ConnectionInfo>& infos) override;
+  void OnMediaMonitorUpdate(DataMediaChannel* media_channel,
+                            const DataMediaInfo& info);
+  bool ShouldSetupDtlsSrtp_n() const override;
   void OnDataReceived(
       const ReceiveDataParams& params, const char* data, size_t len);
   void OnDataChannelError(uint32_t ssrc, DataMediaChannel::Error error);
   void OnDataChannelReadyToSend(bool writable);
   void OnStreamClosedRemotely(uint32_t sid);
 
   std::unique_ptr<DataMediaMonitor> media_monitor_;
   // TODO(pthatcher): Make a separate SctpDataChannel and
   // RtpDataChannel instead of using this.
   DataChannelType data_channel_type_;
   bool ready_to_send_data_;
 
   // Last DataSendParameters sent down to the media_channel() via
   // SetSendParameters.
   DataSendParameters last_send_params_;
   // Last DataRecvParameters sent down to the media_channel() via
   // SetRecvParameters.
   DataRecvParameters last_recv_params_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_PC_CHANNEL_H_