remoting/host/cast_extension_session.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "remoting/host/cast_extension_session.h"
   6
   7 #include "base/bind.h"
   8 #include "base/json/json_reader.h"
   9 #include "base/json/json_writer.h"
  10 #include "base/logging.h"
  11 #include "base/synchronization/waitable_event.h"
  12 #include "net/url_request/url_request_context_getter.h"
  13 #include "remoting/host/cast_video_capturer_adapter.h"
  14 #include "remoting/host/chromium_port_allocator_factory.h"
  15 #include "remoting/host/client_session.h"
  16 #include "remoting/proto/control.pb.h"
  17 #include "remoting/protocol/client_stub.h"
  18 #include "third_party/libjingle/source/talk/app/webrtc/mediastreaminterface.h"
  19 #include "third_party/libjingle/source/talk/app/webrtc/test/fakeconstraints.h"
  20 #include "third_party/libjingle/source/talk/app/webrtc/videosourceinterface.h"
  21
  22 namespace remoting {
  23
  24 // Used as the type attribute of all Cast protocol::ExtensionMessages.
  25 const char kExtensionMessageType[] = "cast_message";
  26
  27 // Top-level keys used in all extension messages between host and client.
  28 // Must keep synced with webapp.
  29 const char kTopLevelData[] = "chromoting_data";
  30 const char kTopLevelSubject[] = "subject";
  31
  32 // Keys used to describe the subject of a cast extension message. WebRTC-related
  33 // message subjects are prepended with "webrtc_".
  34 // Must keep synced with webapp.
  35 const char kSubjectReady[] = "ready";
  36 const char kSubjectTest[] = "test";
  37 const char kSubjectNewCandidate[] = "webrtc_candidate";
  38 const char kSubjectOffer[] = "webrtc_offer";
  39 const char kSubjectAnswer[] = "webrtc_answer";
  40
  41 // WebRTC headers used inside messages with subject = "webrtc_*".
  42 const char kWebRtcCandidate[] = "candidate";
  43 const char kWebRtcSessionDescType[] = "type";
  44 const char kWebRtcSessionDescSDP[] = "sdp";
  45 const char kWebRtcSDPMid[] = "sdpMid";
  46 const char kWebRtcSDPMLineIndex[] = "sdpMLineIndex";
  47
  48 // Media labels used over the PeerConnection.
  49 const char kVideoLabel[] = "cast_video_label";
  50 const char kStreamLabel[] = "stream_label";
  51
  52 // Default STUN server used to construct
  53 // webrtc::PeerConnectionInterface::RTCConfiguration for the PeerConnection.
  54 const char kDefaultStunURI[] = "stun:stun.l.google.com:19302";
  55
  56 const char kWorkerThreadName[] = "CastExtensionSessionWorkerThread";
  57
  58 // Interval between each call to PollPeerConnectionStats().
  59 const int kStatsLogIntervalSec = 10;
  60
  61 // Minimum frame rate for video streaming over the PeerConnection in frames per
  62 // second, added as a media constraint when constructing the video source for
  63 // the Peer Connection.
  64 const int kMinFramesPerSecond = 5;
  65
  66 // A webrtc::SetSessionDescriptionObserver implementation used to receive the
  67 // results of setting local and remote descriptions of the PeerConnection.
  68 class CastSetSessionDescriptionObserver
  69     : public webrtc::SetSessionDescriptionObserver {
  70  public:
  71   static CastSetSessionDescriptionObserver* Create() {
  72     return new rtc::RefCountedObject<CastSetSessionDescriptionObserver>();
  73   }
  74   void OnSuccess() override {
  75     VLOG(1) << "Setting session description succeeded.";
  76   }
  77   void OnFailure(const std::string& error) override {
  78     LOG(ERROR) << "Setting session description failed: " << error;
  79   }
  80
  81  protected:
  82   CastSetSessionDescriptionObserver() {}
  83   ~CastSetSessionDescriptionObserver() override {}
  84
  85   DISALLOW_COPY_AND_ASSIGN(CastSetSessionDescriptionObserver);
  86 };
  87
  88 // A webrtc::CreateSessionDescriptionObserver implementation used to receive the
  89 // results of creating descriptions for this end of the PeerConnection.
  90 class CastCreateSessionDescriptionObserver
  91     : public webrtc::CreateSessionDescriptionObserver {
  92  public:
  93   static CastCreateSessionDescriptionObserver* Create(
  94       CastExtensionSession* session) {
  95     return new rtc::RefCountedObject<CastCreateSessionDescriptionObserver>(
  96         session);
  97   }
  98   void OnSuccess(webrtc::SessionDescriptionInterface* desc) override {
  99     if (cast_extension_session_ == NULL) {
 100       LOG(ERROR)
 101           << "No CastExtensionSession. Creating session description succeeded.";
 102       return;
 103     }
 104     cast_extension_session_->OnCreateSessionDescription(desc);
 105   }
 106   void OnFailure(const std::string& error) override {
 107     if (cast_extension_session_ == NULL) {
 108       LOG(ERROR)
 109           << "No CastExtensionSession. Creating session description failed.";
 110       return;
 111     }
 112     cast_extension_session_->OnCreateSessionDescriptionFailure(error);
 113   }
 114   void SetCastExtensionSession(CastExtensionSession* cast_extension_session) {
 115     cast_extension_session_ = cast_extension_session;
 116   }
 117
 118  protected:
 119   explicit CastCreateSessionDescriptionObserver(CastExtensionSession* session)
 120       : cast_extension_session_(session) {}
 121   ~CastCreateSessionDescriptionObserver() override {}
 122
 123  private:
 124   CastExtensionSession* cast_extension_session_;
 125
 126   DISALLOW_COPY_AND_ASSIGN(CastCreateSessionDescriptionObserver);
 127 };
 128
 129 // A webrtc::StatsObserver implementation used to receive statistics about the
 130 // current PeerConnection.
 131 class CastStatsObserver : public webrtc::StatsObserver {
 132  public:
 133   static CastStatsObserver* Create() {
 134     return new rtc::RefCountedObject<CastStatsObserver>();
 135   }
 136
 137   void OnComplete(const std::vector<webrtc::StatsReport>& reports) override {
 138     typedef webrtc::StatsReport::Values::iterator ValuesIterator;
 139
 140     VLOG(1) << "Received " << reports.size() << " new StatsReports.";
 141
 142     int index;
 143     std::vector<webrtc::StatsReport>::const_iterator it;
 144     for (it = reports.begin(), index = 0; it != reports.end(); ++it, ++index) {
 145       webrtc::StatsReport::Values v = it->values;
 146       VLOG(1) << "Report " << index << ":";
 147       for (ValuesIterator vIt = v.begin(); vIt != v.end(); ++vIt) {
 148         VLOG(1) << "Stat: " << vIt->name << "=" << vIt->value << ".";
 149       }
 150     }
 151   }
 152
 153  protected:
 154   CastStatsObserver() {}
 155   ~CastStatsObserver() override {}
 156
 157   DISALLOW_COPY_AND_ASSIGN(CastStatsObserver);
 158 };
 159
 160 // TODO(aiguha): Fix PeerConnnection-related tear down crash caused by premature
 161 // destruction of cricket::CaptureManager (which occurs on releasing
 162 // |peer_conn_factory_|). See crbug.com/403840.
 163 CastExtensionSession::~CastExtensionSession() {
 164   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 165
 166   // Explicitly clear |create_session_desc_observer_|'s pointer to |this|,
 167   // since the CastExtensionSession is destructing. Otherwise,
 168   // |create_session_desc_observer_| would be left with a dangling pointer.
 169   create_session_desc_observer_->SetCastExtensionSession(NULL);
 170
 171   CleanupPeerConnection();
 172 }
 173
 174 // static
 175 scoped_ptr<CastExtensionSession> CastExtensionSession::Create(
 176     scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner,
 177     scoped_refptr<net::URLRequestContextGetter> url_request_context_getter,
 178     const protocol::NetworkSettings& network_settings,
 179     ClientSessionControl* client_session_control,
 180     protocol::ClientStub* client_stub) {
 181   scoped_ptr<CastExtensionSession> cast_extension_session(
 182       new CastExtensionSession(caller_task_runner,
 183                                url_request_context_getter,
 184                                network_settings,
 185                                client_session_control,
 186                                client_stub));
 187   if (!cast_extension_session->WrapTasksAndSave() ||
 188       !cast_extension_session->InitializePeerConnection()) {
 189     return nullptr;
 190   }
 191   return cast_extension_session.Pass();
 192 }
 193
 194 void CastExtensionSession::OnCreateSessionDescription(
 195     webrtc::SessionDescriptionInterface* desc) {
 196   if (!caller_task_runner_->BelongsToCurrentThread()) {
 197     caller_task_runner_->PostTask(
 198         FROM_HERE,
 199         base::Bind(&CastExtensionSession::OnCreateSessionDescription,
 200                    base::Unretained(this),
 201                    desc));
 202     return;
 203   }
 204
 205   peer_connection_->SetLocalDescription(
 206       CastSetSessionDescriptionObserver::Create(), desc);
 207
 208   scoped_ptr<base::DictionaryValue> json(new base::DictionaryValue());
 209   json->SetString(kWebRtcSessionDescType, desc->type());
 210   std::string subject =
 211       (desc->type() == "offer") ? kSubjectOffer : kSubjectAnswer;
 212   std::string desc_str;
 213   desc->ToString(&desc_str);
 214   json->SetString(kWebRtcSessionDescSDP, desc_str);
 215   std::string json_str;
 216   if (!base::JSONWriter::Write(json.get(), &json_str)) {
 217     LOG(ERROR) << "Failed to serialize sdp message.";
 218     return;
 219   }
 220
 221   SendMessageToClient(subject.c_str(), json_str);
 222 }
 223
 224 void CastExtensionSession::OnCreateSessionDescriptionFailure(
 225     const std::string& error) {
 226   VLOG(1) << "Creating Session Description failed: " << error;
 227 }
 228
 229 // TODO(aiguha): Support the case(s) where we've grabbed the capturer already,
 230 // but another extension reset the video pipeline. We should remove the
 231 // stream from the peer connection here, and then attempt to re-setup the
 232 // peer connection in the OnRenegotiationNeeded() callback.
 233 // See crbug.com/403843.
 234 void CastExtensionSession::OnCreateVideoCapturer(
 235     scoped_ptr<webrtc::DesktopCapturer>* capturer) {
 236   if (has_grabbed_capturer_) {
 237     LOG(ERROR) << "The video pipeline was reset unexpectedly.";
 238     has_grabbed_capturer_ = false;
 239     peer_connection_->RemoveStream(stream_.release());
 240     return;
 241   }
 242
 243   if (received_offer_) {
 244     has_grabbed_capturer_ = true;
 245     if (SetupVideoStream(capturer->Pass())) {
 246       peer_connection_->CreateAnswer(create_session_desc_observer_, NULL);
 247     } else {
 248       has_grabbed_capturer_ = false;
 249       // Ignore the received offer, since we failed to setup a video stream.
 250       received_offer_ = false;
 251     }
 252     return;
 253   }
 254 }
 255
 256 bool CastExtensionSession::ModifiesVideoPipeline() const {
 257   return true;
 258 }
 259
 260 // Returns true if the |message| is a Cast ExtensionMessage, even if
 261 // it was badly formed or a resulting action failed. This is done so that
 262 // the host does not continue to attempt to pass |message| to other
 263 // HostExtensionSessions.
 264 bool CastExtensionSession::OnExtensionMessage(
 265     ClientSessionControl* client_session_control,
 266     protocol::ClientStub* client_stub,
 267     const protocol::ExtensionMessage& message) {
 268   if (message.type() != kExtensionMessageType) {
 269     return false;
 270   }
 271
 272   scoped_ptr<base::Value> value(base::JSONReader::Read(message.data()));
 273   base::DictionaryValue* client_message;
 274   if (!(value && value->GetAsDictionary(&client_message))) {
 275     LOG(ERROR) << "Could not read cast extension message.";
 276     return true;
 277   }
 278
 279   std::string subject;
 280   if (!client_message->GetString(kTopLevelSubject, &subject)) {
 281     LOG(ERROR) << "Invalid Cast Extension Message (missing subject header).";
 282     return true;
 283   }
 284
 285   if (subject == kSubjectOffer && !received_offer_) {
 286     // Reset the video pipeline so we can grab the screen capturer and setup
 287     // a video stream.
 288     if (ParseAndSetRemoteDescription(client_message)) {
 289       received_offer_ = true;
 290       LOG(INFO) << "About to ResetVideoPipeline.";
 291       client_session_control_->ResetVideoPipeline();
 292
 293     }
 294   } else if (subject == kSubjectAnswer) {
 295     ParseAndSetRemoteDescription(client_message);
 296   } else if (subject == kSubjectNewCandidate) {
 297     ParseAndAddICECandidate(client_message);
 298   } else {
 299     VLOG(1) << "Unexpected CastExtension Message: " << message.data();
 300   }
 301   return true;
 302 }
 303
 304 // Private methods ------------------------------------------------------------
 305
 306 CastExtensionSession::CastExtensionSession(
 307     scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner,
 308     scoped_refptr<net::URLRequestContextGetter> url_request_context_getter,
 309     const protocol::NetworkSettings& network_settings,
 310     ClientSessionControl* client_session_control,
 311     protocol::ClientStub* client_stub)
 312     : caller_task_runner_(caller_task_runner),
 313       url_request_context_getter_(url_request_context_getter),
 314       network_settings_(network_settings),
 315       client_session_control_(client_session_control),
 316       client_stub_(client_stub),
 317       stats_observer_(CastStatsObserver::Create()),
 318       received_offer_(false),
 319       has_grabbed_capturer_(false),
 320       signaling_thread_wrapper_(NULL),
 321       worker_thread_wrapper_(NULL),
 322       worker_thread_(kWorkerThreadName) {
 323   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 324   DCHECK(url_request_context_getter_.get());
 325   DCHECK(client_session_control_);
 326   DCHECK(client_stub_);
 327
 328   // The worker thread is created with base::MessageLoop::TYPE_IO because
 329   // the PeerConnection performs some port allocation operations on this thread
 330   // that require it. See crbug.com/404013.
 331   base::Thread::Options options(base::MessageLoop::TYPE_IO, 0);
 332   worker_thread_.StartWithOptions(options);
 333   worker_task_runner_ = worker_thread_.task_runner();
 334 }
 335
 336 bool CastExtensionSession::ParseAndSetRemoteDescription(
 337     base::DictionaryValue* message) {
 338   DCHECK(peer_connection_.get() != NULL);
 339
 340   base::DictionaryValue* message_data;
 341   if (!message->GetDictionary(kTopLevelData, &message_data)) {
 342     LOG(ERROR) << "Invalid Cast Extension Message (missing data).";
 343     return false;
 344   }
 345
 346   std::string webrtc_type;
 347   if (!message_data->GetString(kWebRtcSessionDescType, &webrtc_type)) {
 348     LOG(ERROR)
 349         << "Invalid Cast Extension Message (missing webrtc type header).";
 350     return false;
 351   }
 352
 353   std::string sdp;
 354   if (!message_data->GetString(kWebRtcSessionDescSDP, &sdp)) {
 355     LOG(ERROR) << "Invalid Cast Extension Message (missing webrtc sdp header).";
 356     return false;
 357   }
 358
 359   webrtc::SdpParseError error;
 360   webrtc::SessionDescriptionInterface* session_description(
 361       webrtc::CreateSessionDescription(webrtc_type, sdp, &error));
 362
 363   if (!session_description) {
 364     LOG(ERROR) << "Invalid Cast Extension Message (could not parse sdp).";
 365     VLOG(1) << "SdpParseError was: " << error.description;
 366     return false;
 367   }
 368
 369   peer_connection_->SetRemoteDescription(
 370       CastSetSessionDescriptionObserver::Create(), session_description);
 371   return true;
 372 }
 373
 374 bool CastExtensionSession::ParseAndAddICECandidate(
 375     base::DictionaryValue* message) {
 376   DCHECK(peer_connection_.get() != NULL);
 377
 378   base::DictionaryValue* message_data;
 379   if (!message->GetDictionary(kTopLevelData, &message_data)) {
 380     LOG(ERROR) << "Invalid Cast Extension Message (missing data).";
 381     return false;
 382   }
 383
 384   std::string candidate_str;
 385   std::string sdp_mid;
 386   int sdp_mlineindex = 0;
 387   if (!message_data->GetString(kWebRtcSDPMid, &sdp_mid) ||
 388       !message_data->GetInteger(kWebRtcSDPMLineIndex, &sdp_mlineindex) ||
 389       !message_data->GetString(kWebRtcCandidate, &candidate_str)) {
 390     LOG(ERROR) << "Invalid Cast Extension Message (could not parse).";
 391     return false;
 392   }
 393
 394   rtc::scoped_ptr<webrtc::IceCandidateInterface> candidate(
 395       webrtc::CreateIceCandidate(sdp_mid, sdp_mlineindex, candidate_str));
 396   if (!candidate.get()) {
 397     LOG(ERROR)
 398         << "Invalid Cast Extension Message (could not create candidate).";
 399     return false;
 400   }
 401
 402   if (!peer_connection_->AddIceCandidate(candidate.get())) {
 403     LOG(ERROR) << "Failed to apply received ICE Candidate to PeerConnection.";
 404     return false;
 405   }
 406
 407   VLOG(1) << "Received and Added ICE Candidate: " << candidate_str;
 408
 409   return true;
 410 }
 411
 412 bool CastExtensionSession::SendMessageToClient(const std::string& subject,
 413                                                const std::string& data) {
 414   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 415
 416   if (client_stub_ == NULL) {
 417     LOG(ERROR) << "No Client Stub. Cannot send message to client.";
 418     return false;
 419   }
 420
 421   base::DictionaryValue message_dict;
 422   message_dict.SetString(kTopLevelSubject, subject);
 423   message_dict.SetString(kTopLevelData, data);
 424   std::string message_json;
 425
 426   if (!base::JSONWriter::Write(&message_dict, &message_json)) {
 427     LOG(ERROR) << "Failed to serialize JSON message.";
 428     return false;
 429   }
 430
 431   protocol::ExtensionMessage message;
 432   message.set_type(kExtensionMessageType);
 433   message.set_data(message_json);
 434   client_stub_->DeliverHostMessage(message);
 435   return true;
 436 }
 437
 438 void CastExtensionSession::EnsureTaskAndSetSend(rtc::Thread** ptr,
 439                                                 base::WaitableEvent* event) {
 440   jingle_glue::JingleThreadWrapper::EnsureForCurrentMessageLoop();
 441   jingle_glue::JingleThreadWrapper::current()->set_send_allowed(true);
 442   *ptr = jingle_glue::JingleThreadWrapper::current();
 443
 444   if (event != NULL) {
 445     event->Signal();
 446   }
 447 }
 448
 449 bool CastExtensionSession::WrapTasksAndSave() {
 450   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 451
 452   EnsureTaskAndSetSend(&signaling_thread_wrapper_);
 453   if (signaling_thread_wrapper_ == NULL)
 454     return false;
 455
 456   base::WaitableEvent wrap_worker_thread_event(true, false);
 457   worker_task_runner_->PostTask(
 458       FROM_HERE,
 459       base::Bind(&CastExtensionSession::EnsureTaskAndSetSend,
 460                  base::Unretained(this),
 461                  &worker_thread_wrapper_,
 462                  &wrap_worker_thread_event));
 463   wrap_worker_thread_event.Wait();
 464
 465   return (worker_thread_wrapper_ != NULL);
 466 }
 467
 468 bool CastExtensionSession::InitializePeerConnection() {
 469   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 470   DCHECK(!peer_conn_factory_);
 471   DCHECK(!peer_connection_);
 472   DCHECK(worker_thread_wrapper_ != NULL);
 473   DCHECK(signaling_thread_wrapper_ != NULL);
 474
 475   peer_conn_factory_ = webrtc::CreatePeerConnectionFactory(
 476       worker_thread_wrapper_, signaling_thread_wrapper_, NULL, NULL, NULL);
 477
 478   if (!peer_conn_factory_.get()) {
 479     CleanupPeerConnection();
 480     return false;
 481   }
 482
 483   VLOG(1) << "Created PeerConnectionFactory successfully.";
 484
 485   webrtc::PeerConnectionInterface::IceServers servers;
 486   webrtc::PeerConnectionInterface::IceServer server;
 487   server.uri = kDefaultStunURI;
 488   servers.push_back(server);
 489   webrtc::PeerConnectionInterface::RTCConfiguration rtc_config;
 490   rtc_config.servers = servers;
 491
 492   // DTLS-SRTP is the preferred encryption method. If set to kValueFalse, the
 493   // peer connection uses SDES. Disabling SDES as well will cause the peer
 494   // connection to fail to connect.
 495   // Note: For protection and unprotection of SRTP packets, the libjingle
 496   // ENABLE_EXTERNAL_AUTH flag must not be set.
 497   webrtc::FakeConstraints constraints;
 498   constraints.AddMandatory(webrtc::MediaConstraintsInterface::kEnableDtlsSrtp,
 499                            webrtc::MediaConstraintsInterface::kValueTrue);
 500
 501   rtc::scoped_refptr<webrtc::PortAllocatorFactoryInterface>
 502       port_allocator_factory = ChromiumPortAllocatorFactory::Create(
 503           network_settings_, url_request_context_getter_);
 504
 505   peer_connection_ = peer_conn_factory_->CreatePeerConnection(
 506       rtc_config, &constraints, port_allocator_factory, NULL, this);
 507
 508   if (!peer_connection_.get()) {
 509     CleanupPeerConnection();
 510     return false;
 511   }
 512
 513   VLOG(1) << "Created PeerConnection successfully.";
 514
 515   create_session_desc_observer_ =
 516       CastCreateSessionDescriptionObserver::Create(this);
 517
 518   // Send a test message to the client. Then, notify the client to start
 519   // webrtc offer/answer negotiation.
 520   if (!SendMessageToClient(kSubjectTest, "Hello, client.") ||
 521       !SendMessageToClient(kSubjectReady, "Host ready to receive offers.")) {
 522     LOG(ERROR) << "Failed to send messages to client.";
 523     return false;
 524   }
 525
 526   return true;
 527 }
 528
 529 bool CastExtensionSession::SetupVideoStream(
 530     scoped_ptr<webrtc::DesktopCapturer> desktop_capturer) {
 531   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 532   DCHECK(desktop_capturer);
 533
 534   if (stream_) {
 535     VLOG(1) << "Already added MediaStream. Aborting Setup.";
 536     return false;
 537   }
 538
 539   scoped_ptr<CastVideoCapturerAdapter> cast_video_capturer_adapter(
 540       new CastVideoCapturerAdapter(desktop_capturer.Pass()));
 541
 542   // Set video stream constraints.
 543   webrtc::FakeConstraints video_constraints;
 544   video_constraints.AddMandatory(
 545       webrtc::MediaConstraintsInterface::kMinFrameRate, kMinFramesPerSecond);
 546
 547   rtc::scoped_refptr<webrtc::VideoTrackInterface> video_track =
 548       peer_conn_factory_->CreateVideoTrack(
 549           kVideoLabel,
 550           peer_conn_factory_->CreateVideoSource(
 551               cast_video_capturer_adapter.release(), &video_constraints));
 552
 553   stream_ = peer_conn_factory_->CreateLocalMediaStream(kStreamLabel);
 554
 555   if (!stream_->AddTrack(video_track) ||
 556       !peer_connection_->AddStream(stream_)) {
 557     return false;
 558   }
 559
 560   VLOG(1) << "Setup video stream successfully.";
 561
 562   return true;
 563 }
 564
 565 void CastExtensionSession::PollPeerConnectionStats() {
 566   if (!connection_active()) {
 567     VLOG(1) << "Cannot poll stats while PeerConnection is inactive.";
 568   }
 569   rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> video_track =
 570       stream_->FindVideoTrack(kVideoLabel);
 571   peer_connection_->GetStats(
 572       stats_observer_,
 573       video_track.release(),
 574       webrtc::PeerConnectionInterface::kStatsOutputLevelStandard);
 575 }
 576
 577 void CastExtensionSession::CleanupPeerConnection() {
 578   peer_connection_->Close();
 579   peer_connection_ = NULL;
 580   stream_ = NULL;
 581   peer_conn_factory_ = NULL;
 582   worker_thread_.Stop();
 583 }
 584
 585 bool CastExtensionSession::connection_active() const {
 586   return peer_connection_.get() != NULL;
 587 }
 588
 589 // webrtc::PeerConnectionObserver implementation -------------------------------
 590 void CastExtensionSession::OnSignalingChange(
 591     webrtc::PeerConnectionInterface::SignalingState new_state) {
 592   VLOG(1) << "PeerConnectionObserver: SignalingState changed to:" << new_state;
 593 }
 594
 595 void CastExtensionSession::OnStateChange(
 596     webrtc::PeerConnectionObserver::StateType state_changed) {
 597   VLOG(1) << "PeerConnectionObserver: StateType changed to: " << state_changed;
 598 }
 599
 600 void CastExtensionSession::OnAddStream(webrtc::MediaStreamInterface* stream) {
 601   VLOG(1) << "PeerConnectionObserver: stream added: " << stream->label();
 602 }
 603
 604 void CastExtensionSession::OnRemoveStream(
 605     webrtc::MediaStreamInterface* stream) {
 606   VLOG(1) << "PeerConnectionObserver: stream removed: " << stream->label();
 607 }
 608
 609 void CastExtensionSession::OnDataChannel(
 610     webrtc::DataChannelInterface* data_channel) {
 611   VLOG(1) << "PeerConnectionObserver: data channel: " << data_channel->label();
 612 }
 613
 614 void CastExtensionSession::OnRenegotiationNeeded() {
 615   VLOG(1) << "PeerConnectionObserver: renegotiation needed.";
 616 }
 617
 618 void CastExtensionSession::OnIceConnectionChange(
 619     webrtc::PeerConnectionInterface::IceConnectionState new_state) {
 620   VLOG(1) << "PeerConnectionObserver: IceConnectionState changed to: "
 621           << new_state;
 622
 623   // TODO(aiguha): Maybe start timer only if enabled by command-line flag or
 624   // at a particular verbosity level.
 625   if (!stats_polling_timer_.IsRunning() &&
 626       new_state == webrtc::PeerConnectionInterface::kIceConnectionConnected) {
 627     stats_polling_timer_.Start(
 628         FROM_HERE,
 629         base::TimeDelta::FromSeconds(kStatsLogIntervalSec),
 630         this,
 631         &CastExtensionSession::PollPeerConnectionStats);
 632   }
 633 }
 634
 635 void CastExtensionSession::OnIceGatheringChange(
 636     webrtc::PeerConnectionInterface::IceGatheringState new_state) {
 637   VLOG(1) << "PeerConnectionObserver: IceGatheringState changed to: "
 638           << new_state;
 639 }
 640
 641 void CastExtensionSession::OnIceComplete() {
 642   VLOG(1) << "PeerConnectionObserver: all ICE candidates found.";
 643 }
 644
 645 void CastExtensionSession::OnIceCandidate(
 646     const webrtc::IceCandidateInterface* candidate) {
 647   std::string candidate_str;
 648   if (!candidate->ToString(&candidate_str)) {
 649     LOG(ERROR) << "PeerConnectionObserver: failed to serialize candidate.";
 650     return;
 651   }
 652   scoped_ptr<base::DictionaryValue> json(new base::DictionaryValue());
 653   json->SetString(kWebRtcSDPMid, candidate->sdp_mid());
 654   json->SetInteger(kWebRtcSDPMLineIndex, candidate->sdp_mline_index());
 655   json->SetString(kWebRtcCandidate, candidate_str);
 656   std::string json_str;
 657   if (!base::JSONWriter::Write(json.get(), &json_str)) {
 658     LOG(ERROR) << "Failed to serialize candidate message.";
 659     return;
 660   }
 661   SendMessageToClient(kSubjectNewCandidate, json_str);
 662 }
 663
 664 }  // namespace remoting