WIP: Move the creation of AudioCodecFactory into PeerConnectionFactory.

webrtc/modules/audio_coding/neteq/neteq_impl.cc

Index: webrtc/modules/audio_coding/neteq/neteq_impl.cc
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index b4ba650fefb3e2066401104b2b6a5b5b1b630530..022299b300653efd2a437c8a5d1e96d5672b1706 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -55,10 +55,12 @@
 
 namespace webrtc {
 
-NetEqImpl::Dependencies::Dependencies(const NetEq::Config& config)
+NetEqImpl::Dependencies::Dependencies(
+    const NetEq::Config& config,
+    std::shared_ptr<AudioDecoderFactory> decoder_factory)
     : tick_timer(new TickTimer),
       buffer_level_filter(new BufferLevelFilter),
-      decoder_database(new DecoderDatabase(CreateBuiltinAudioDecoderFactory())),
+      decoder_database(new DecoderDatabase(std::move(decoder_factory))),
       delay_peak_detector(new DelayPeakDetector(tick_timer.get())),
       delay_manager(new DelayManager(config.max_packets_in_buffer,
                                      delay_peak_detector.get(),