Revert "Revert "Enables PeerConnectionFactory using external fec controller""

This reverts commit 00733015fafbbc61ddc12dfdc88b21a9fcd9d122.

Reason for revert: The reason for a downstream test failure on the original commit and a workaround has been found. Solution is to keep a PeerConnectionFactory constructor implementation as the same as before.

Original change's description:
> Revert "Enables PeerConnectionFactory using external fec controller"
>
> This reverts commit 4f07bdb25567d8ef528311e0b50a62c61d543fc3.
>
> Reason for revert: Speculatively reverting, because downstream test is now hitting "PeerConnectionFactory.initialize was not called before creating a PeerConnectionFactory" error, even though it did call initialize. I don't see how any change in this CL could cause that, but it's the only CL on the blamelist, and it does modify PeerConnectionFactory.java
>
> Original change's description:
> > Enables PeerConnectionFactory using external fec controller
> >
> > Bug: webrtc:8799
> > Change-Id: Ieb2cf6163b9a83844ab9ed4822b4a7f1db4c24b8
> > Reviewed-on: https://webrtc-review.googlesource.com/43961
> > Commit-Queue: Ying Wang <yinwa@webrtc.org>
> > Reviewed-by: Stefan Holmer <stefan@webrtc.org>
> > Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> > Reviewed-by: Niels Moller <nisse@webrtc.org>
> > Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#22038}
>
> TBR=sakal@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org,stefan@webrtc.org,yinwa@webrtc.org
>
> Change-Id: I95868c35d6f9973e0ebf563814cd71d0fcbd433d
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:8799
> Reviewed-on: https://webrtc-review.googlesource.com/54080
> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
> Commit-Queue: Taylor Brandstetter <deadbeef@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22040}

TBR=deadbeef@webrtc.org,sakal@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org,stefan@webrtc.org,yinwa@webrtc.org

Bug: webrtc:8799
Change-Id: If9f3292bfcc739782967530c49f006d0abbc38a8
Reviewed-on: https://webrtc-review.googlesource.com/55400
Commit-Queue: Ying Wang <yinwa@webrtc.org>
Reviewed-by: Ying Wang <yinwa@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22100}
diff --git a/api/peerconnectioninterface.h b/api/peerconnectioninterface.h
index 5784d95..63912b2 100644
--- a/api/peerconnectioninterface.h
+++ b/api/peerconnectioninterface.h
@@ -83,6 +83,7 @@
 #include "api/call/callfactoryinterface.h"
 #include "api/datachannelinterface.h"
 #include "api/dtmfsenderinterface.h"
+#include "api/fec_controller.h"
 #include "api/jsep.h"
 #include "api/mediastreaminterface.h"
 #include "api/rtcerror.h"
@@ -1296,6 +1297,27 @@
     rtc::scoped_refptr<AudioMixer> audio_mixer,
     rtc::scoped_refptr<AudioProcessing> audio_processing);
 
+// Create a new instance of PeerConnectionFactoryInterface with optional
+// external audio mixer, audio processing, and fec controller modules.
+//
+// If |audio_mixer| is null, an internal audio mixer will be created and used.
+// If |audio_processing| is null, an internal audio processing module will be
+// created and used.
+// If |fec_controller_factory| is null, an internal fec controller module will
+// be created and used.
+rtc::scoped_refptr<PeerConnectionFactoryInterface> CreatePeerConnectionFactory(
+    rtc::Thread* network_thread,
+    rtc::Thread* worker_thread,
+    rtc::Thread* signaling_thread,
+    AudioDeviceModule* default_adm,
+    rtc::scoped_refptr<AudioEncoderFactory> audio_encoder_factory,
+    rtc::scoped_refptr<AudioDecoderFactory> audio_decoder_factory,
+    cricket::WebRtcVideoEncoderFactory* video_encoder_factory,
+    cricket::WebRtcVideoDecoderFactory* video_decoder_factory,
+    rtc::scoped_refptr<AudioMixer> audio_mixer,
+    rtc::scoped_refptr<AudioProcessing> audio_processing,
+    std::unique_ptr<FecControllerFactoryInterface> fec_controller_factory);
+
 // Create a new instance of PeerConnectionFactoryInterface with optional video
 // codec factories. These video factories represents all video codecs, i.e. no
 // extra internal video codecs will be added.
@@ -1385,6 +1407,16 @@
     std::unique_ptr<CallFactoryInterface> call_factory,
     std::unique_ptr<RtcEventLogFactoryInterface> event_log_factory);
 
+rtc::scoped_refptr<PeerConnectionFactoryInterface>
+CreateModularPeerConnectionFactory(
+    rtc::Thread* network_thread,
+    rtc::Thread* worker_thread,
+    rtc::Thread* signaling_thread,
+    std::unique_ptr<cricket::MediaEngineInterface> media_engine,
+    std::unique_ptr<CallFactoryInterface> call_factory,
+    std::unique_ptr<RtcEventLogFactoryInterface> event_log_factory,
+    std::unique_ptr<FecControllerFactoryInterface> fec_controller_factory);
+
 }  // namespace webrtc
 
 #endif  // API_PEERCONNECTIONINTERFACE_H_