Build WebRTC with data channel only.

webrtc/pc/mediacontroller.cc

Index: webrtc/pc/mediacontroller.cc
diff --git a/webrtc/pc/mediacontroller.cc b/webrtc/pc/mediacontroller.cc
index fa8acadddcc5229b7126c4b4c2c9cdc7b34b25fb..2203a1f4ff47d1e69aa01954b2716c4bd067e312 100644
--- a/webrtc/pc/mediacontroller.cc
+++ b/webrtc/pc/mediacontroller.cc
@@ -53,9 +53,11 @@ class MediaController : public webrtc::MediaControllerInterface,
   }
   webrtc::Call* call_w() override {
     RTC_DCHECK(worker_thread_->IsCurrent());
+#ifdef HAVE_MEDIA
     if (!call_) {
       call_.reset(webrtc::Call::Create(call_config_));
     }
+#endif
     return call_.get();
   }
   cricket::ChannelManager* channel_manager() const override {
@@ -66,8 +68,10 @@ class MediaController : public webrtc::MediaControllerInterface,
  private:
   void Construct_w(cricket::MediaEngineInterface* media_engine) {
     RTC_DCHECK(worker_thread_->IsCurrent());
+#ifdef HAVE_MEDIA
     RTC_DCHECK(media_engine);
     call_config_.audio_state = media_engine->GetAudioState();
+#endif
     call_config_.bitrate_config.min_bitrate_bps = kMinBandwidthBps;
     call_config_.bitrate_config.start_bitrate_bps = kStartBandwidthBps;
     call_config_.bitrate_config.max_bitrate_bps = kMaxBandwidthBps;