Move NetEq headers to api/

This CL also introduces NetEqFactory and NetEqControllerFactory
interfaces, as well as several convenience classes for working with
them: DefaultNetEqFactory, DefaultNetEqControllerFactory and
CustomNetEqFactory.

Bug: webrtc:11005
Change-Id: I1e8fc5154636ac2aad1a856828f80a2a758ad392
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/156945
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29671}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index ab99e73..3321999 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -597,6 +597,26 @@
   ]
 }
 
+rtc_source_set("neteq_factory_with_codecs") {
+  visibility = [ "*" ]
+  testonly = true
+  sources = [
+    "test/neteq_factory_with_codecs.cc",
+    "test/neteq_factory_with_codecs.h",
+  ]
+
+  deps = [
+    ":scoped_refptr",
+    "../modules/audio_coding:neteq",
+    "../system_wrappers:system_wrappers",
+    "audio_codecs:audio_codecs_api",
+    "audio_codecs:builtin_audio_decoder_factory",
+    "neteq:default_neteq_controller_factory",
+    "neteq:neteq_api",
+    "neteq:neteq_controller_api",
+  ]
+}
+
 rtc_source_set("function_view") {
   visibility = [ "*" ]
   sources = [