Injectable audio encoders: Moved audio encoder, factory and builtin factory to api/.

webrtc/api/audio_codecs/BUILD.gn

Index: webrtc/api/audio_codecs/BUILD.gn
diff --git a/webrtc/api/audio_codecs/BUILD.gn b/webrtc/api/audio_codecs/BUILD.gn
index c003df838da23c0827d4614bd11c5cdc7fbc4127..0b51db8bcc2a62934952a20a18c4987b7409b585 100644
--- a/webrtc/api/audio_codecs/BUILD.gn
+++ b/webrtc/api/audio_codecs/BUILD.gn
@@ -17,6 +17,9 @@ rtc_source_set("audio_codecs_api") {
     "audio_decoder.cc",
     "audio_decoder.h",
     "audio_decoder_factory.h",
+    "audio_encoder.cc",
+    "audio_encoder.h",
+    "audio_encoder_factory.h",
     "audio_format.cc",
     "audio_format.h",
   ]
@@ -37,3 +40,15 @@ rtc_static_library("builtin_audio_decoder_factory") {
     "../../modules/audio_coding:builtin_audio_decoder_factory_internal",
   ]
 }
+
+rtc_static_library("builtin_audio_encoder_factory") {
+  sources = [
+    "builtin_audio_encoder_factory.cc",
+    "builtin_audio_encoder_factory.h",
+  ]
+  deps = [
+    ":audio_codecs_api",
+    "../../base:rtc_base_approved",
+    "../../modules/audio_coding:builtin_audio_encoder_factory_internal",
+  ]
+}