Build WebRTC with data channel only.

webrtc/pc/peerconnectionfactory.cc

Index: webrtc/pc/peerconnectionfactory.cc
diff --git a/webrtc/pc/peerconnectionfactory.cc b/webrtc/pc/peerconnectionfactory.cc
index 777bac1eb59aadd49bcc9af1d44ac66e9d02276f..a7bd4290d4e4e42160d46cb75232e5e0a2b7a2b4 100644
--- a/webrtc/pc/peerconnectionfactory.cc
+++ b/webrtc/pc/peerconnectionfactory.cc
@@ -37,6 +37,20 @@
 
 namespace webrtc {
 
+rtc::scoped_refptr<AudioEncoderFactory> CreateBuiltinAudioEncoderFactoryImpl();
+
+rtc::scoped_refptr<AudioDecoderFactory> CreateBuiltinAudioDecoderFactoryImpl();
+
+std::unique_ptr<cricket::MediaEngineInterface> CreateMediaEngineImpl(
+    webrtc::AudioDeviceModule* adm,
+    const rtc::scoped_refptr<webrtc::AudioEncoderFactory>&
+        audio_encoder_factory,
+    const rtc::scoped_refptr<webrtc::AudioDecoderFactory>&
+        audio_decoder_factory,
+    cricket::WebRtcVideoEncoderFactory* video_encoder_factory,
+    cricket::WebRtcVideoDecoderFactory* video_decoder_factory,
+    rtc::scoped_refptr<webrtc::AudioMixer> audio_mixer);

[Taylor Brandstetter, 2017/05/18 17:57:05]

Are the extra "Impl" methods needed here? It seems like the "nullimpl.cc" files
could just implement CreateBuiltinAudioEncoderFactory,
CreateBuiltinAudioDecoderFactory and WebRtcMediaEngineFactory::Create directly.

And actually, same for CreateCallImpl and Call::Create.

[Zhi Huang, 2017/05/23 03:40:35]

I think we still need CreateBuiltinAudioEncoderFactoryImpl otherwise this method
would be define twice and we can't just remove the old one since chromium is
depending on it.

I'll remove others.

+
 rtc::scoped_refptr<PeerConnectionFactoryInterface> CreatePeerConnectionFactory(
     rtc::scoped_refptr<AudioEncoderFactory> audio_encoder_factory,
     rtc::scoped_refptr<AudioDecoderFactory> audio_decoder_factory) {
@@ -56,8 +70,8 @@ rtc::scoped_refptr<PeerConnectionFactoryInterface> CreatePeerConnectionFactory(
 
 rtc::scoped_refptr<PeerConnectionFactoryInterface>
 CreatePeerConnectionFactory() {
-  return CreatePeerConnectionFactory(CreateBuiltinAudioEncoderFactory(),
-                                     CreateBuiltinAudioDecoderFactory());
+  return CreatePeerConnectionFactory(CreateBuiltinAudioEncoderFactoryImpl(),
+                                     CreateBuiltinAudioDecoderFactoryImpl());
 }
 
 rtc::scoped_refptr<PeerConnectionFactoryInterface> CreatePeerConnectionFactory(
@@ -127,8 +141,9 @@ CreatePeerConnectionFactoryWithAudioMixer(
     rtc::scoped_refptr<AudioMixer> audio_mixer) {
   return CreatePeerConnectionFactoryWithAudioMixer(
       network_thread, worker_thread, signaling_thread, default_adm,
-      CreateBuiltinAudioEncoderFactory(), CreateBuiltinAudioDecoderFactory(),
-      encoder_factory, decoder_factory, audio_mixer);
+      CreateBuiltinAudioEncoderFactoryImpl(),
+      CreateBuiltinAudioDecoderFactoryImpl(), encoder_factory, decoder_factory,
+      audio_mixer);
 }
 
 PeerConnectionFactory::PeerConnectionFactory(
@@ -385,12 +400,10 @@ rtc::Thread* PeerConnectionFactory::network_thread() {
 std::unique_ptr<cricket::MediaEngineInterface>
 PeerConnectionFactory::CreateMediaEngine_w() {
   RTC_DCHECK(worker_thread_ == rtc::Thread::Current());
-  return std::unique_ptr<cricket::MediaEngineInterface>(
-      cricket::WebRtcMediaEngineFactory::Create(
-          default_adm_.get(), audio_encoder_factory_,
-          audio_decoder_factory_,
-          video_encoder_factory_.get(), video_decoder_factory_.get(),
-          external_audio_mixer_));
+  return CreateMediaEngineImpl(
+      default_adm_.get(), audio_encoder_factory_, audio_decoder_factory_,
+      video_encoder_factory_.get(), video_decoder_factory_.get(),
+      external_audio_mixer_);
 }
 
 }  // namespace webrtc