Adding FecController to audio network adaptor.

BUG=webrtc:6303

Review-Url: https://codereview.webrtc.org/2337103006
Cr-Commit-Position: refs/heads/master@{#14351}
diff --git a/webrtc/modules/audio_coding/BUILD.gn b/webrtc/modules/audio_coding/BUILD.gn
index b55829d..eaf2e74 100644
--- a/webrtc/modules/audio_coding/BUILD.gn
+++ b/webrtc/modules/audio_coding/BUILD.gn
@@ -711,6 +711,8 @@
     "audio_network_adaptor/controller_manager.h",
     "audio_network_adaptor/dtx_controller.cc",
     "audio_network_adaptor/dtx_controller.h",
+    "audio_network_adaptor/fec_controller.cc",
+    "audio_network_adaptor/fec_controller.h",
     "audio_network_adaptor/frame_length_controller.cc",
     "audio_network_adaptor/frame_length_controller.h",
     "audio_network_adaptor/include/audio_network_adaptor.h",