Build WebRTC with data channel only.

webrtc/pc/channelmanager.cc

 /*
  *  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.
  */
 
@@ skipping 122 matching lines @@
   }
   RTC_DCHECK(network_thread_);
   RTC_DCHECK(worker_thread_);
   if (!network_thread_->IsCurrent()) {
     // Do not allow invoking calls to other threads on the network thread.
     network_thread_->Invoke<bool>(
         RTC_FROM_HERE,
         rtc::Bind(&rtc::Thread::SetAllowBlockingCalls, network_thread_, false));
   }
 
+#if defined(HAVE_WEBRTC_VOICE) && defined(HAVE_WEBRTC_VIDEO)

[Taylor Brandstetter, 2017/05/11 04:43:11]

Should be an ||?

[Zhi Huang, 2017/05/12 20:05:33]

Done.

   initialized_ = worker_thread_->Invoke<bool>(
       RTC_FROM_HERE, Bind(&ChannelManager::InitMediaEngine_w, this));
+#else
+  initialized_ = true;
+#endif
   RTC_DCHECK(initialized_);
   return initialized_;
 }
 
 bool ChannelManager::InitMediaEngine_w() {
   RTC_DCHECK(worker_thread_ == rtc::Thread::Current());
+  RTC_DCHECK(media_engine_);
   return media_engine_->Init();
 }
 
 void ChannelManager::Terminate() {
   RTC_DCHECK(initialized_);
   if (!initialized_) {
     return;
   }
   worker_thread_->Invoke<void>(RTC_FROM_HERE,
                                Bind(&ChannelManager::Terminate_w, this));
@@ skipping 56 matching lines @@
     rtc::PacketTransportInternal* rtp_packet_transport,
     rtc::PacketTransportInternal* rtcp_packet_transport,
     rtc::Thread* signaling_thread,
     const std::string& content_name,
     bool srtp_required,
     const AudioOptions& options) {
   RTC_DCHECK(initialized_);
   RTC_DCHECK(worker_thread_ == rtc::Thread::Current());
   RTC_DCHECK(nullptr != call);
 
+#ifndef HAVE_WEBRTC_VOICE
+  return nullptr;

[Taylor Brandstetter, 2017/05/11 04:43:11]

I'm curious, why was this necessary?

[Zhi Huang, 2017/05/12 20:05:33]

Because the media_engine_ here would be a nullptr.

+#endif
   VoiceMediaChannel* media_channel = media_engine_->CreateChannel(
       call, media_config, options);
   if (!media_channel)
     return nullptr;
 
   VoiceChannel* voice_channel =
       new VoiceChannel(worker_thread_, network_thread_, signaling_thread,
                        media_engine_.get(), media_channel, content_name,
                        rtcp_packet_transport == nullptr, srtp_required);
 
@@ skipping 189 matching lines @@
                           media_engine_.get(), file, max_size_bytes));
 }
 
 void ChannelManager::StopAecDump() {
   worker_thread_->Invoke<void>(
       RTC_FROM_HERE,
       Bind(&MediaEngineInterface::StopAecDump, media_engine_.get()));
 }
 
 }  // namespace cricket