Enable injection of a custom NetEqFactory into PeerConnectionFactory.

Injecting both a custom NetEqFactory and an AudioDecoderFactory is not
supported, in that case the AudioDecoderFactory should be wrapped inside
the NetEqFactory.

Bug: webrtc:11005
Change-Id: I4e311eb1bfa03c91bca587d70540e81829f881c9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158720
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29673}
diff --git a/audio/BUILD.gn b/audio/BUILD.gn
index 927c948..e64b76f 100644
--- a/audio/BUILD.gn
+++ b/audio/BUILD.gn
@@ -50,6 +50,7 @@
     "../api/crypto:frame_decryptor_interface",
     "../api/crypto:frame_encryptor_interface",
     "../api/crypto:options",
+    "../api/neteq:neteq_api",
     "../api/rtc_event_log",
     "../api/task_queue",
     "../api/transport/media:media_transport_interface",