Build WebRTC with data channel only.

webrtc/pc/channelmanager.cc

Index: webrtc/pc/channelmanager.cc
diff --git a/webrtc/pc/channelmanager.cc b/webrtc/pc/channelmanager.cc
index 995a07bf0562c6de6e43f000104be5934b4a5f60..3b7fff05c954a1b5acc9201bdd94b1fb7f69e0d4 100644
--- a/webrtc/pc/channelmanager.cc
+++ b/webrtc/pc/channelmanager.cc
@@ -149,7 +149,12 @@ bool ChannelManager::Init() {
 
 bool ChannelManager::InitMediaEngine_w() {
   RTC_DCHECK(worker_thread_ == rtc::Thread::Current());
+#ifdef HAVE_MEDIA
+  RTC_DCHECK(media_engine_);
   return media_engine_->Init();
+#else
+  return true;
+#endif

[pthatcher1, 2017/05/03 18:05:53]

Would it be easier to just not call InitMediaEngine_w in ChannelManager::Init()?

[Zhi Huang, 2017/05/04 01:08:03]

I guess we still need to do something like this:

#ifdef HAVE_MEDIA
  initialized_ = worker_thread_->Invoke<bool>(
      RTC_FROM_HERE, Bind(&ChannelManager::InitMediaEngine_w, this));
#else
  initialized_ = true;
#endif

 }
 
 void ChannelManager::Terminate() {
@@ -222,6 +227,9 @@ VoiceChannel* ChannelManager::CreateVoiceChannel_w(
   RTC_DCHECK(worker_thread_ == rtc::Thread::Current());
   RTC_DCHECK(nullptr != media_controller);
 
+#ifndef HAVE_MEDIA
+  return nullptr;
+#endif
   VoiceMediaChannel* media_channel = media_engine_->CreateChannel(
       media_controller->call_w(), media_controller->config(), options);
   if (!media_channel)