Make header files self contained.

This CL adds #includes to header files in order to make them
self contained after the preprocessor pass.

Bug: b/251890128
Change-Id: I81c3ba38fb8ab8a2bbd151ba99aa871fae9f1b1b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/278422
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38327}

api/audio_codecs/g722/BUILD.gn

@@ -15,6 +15,7 @@ if (is_android) {
 rtc_source_set("audio_encoder_g722_config") {
   visibility = [ "*" ]
   sources = [ "audio_encoder_g722_config.h" ]
+  deps = [ "..:audio_codecs_api" ]
 }
 
 rtc_library("audio_encoder_g722") {

api/audio_codecs/g722/audio_encoder_g722_config.h

@@ -11,6 +11,8 @@
 #ifndef API_AUDIO_CODECS_G722_AUDIO_ENCODER_G722_CONFIG_H_
 #define API_AUDIO_CODECS_G722_AUDIO_ENCODER_G722_CONFIG_H_
 
+#include "api/audio_codecs/audio_encoder.h"
+
 namespace webrtc {
 
 struct AudioEncoderG722Config {

api/audio_codecs/opus/BUILD.gn

@@ -20,9 +20,7 @@ rtc_library("audio_encoder_opus_config") {
     "audio_encoder_opus_config.cc",
     "audio_encoder_opus_config.h",
   ]
-  deps = [
-    "../../../rtc_base/system:rtc_export",
-  ]
+  deps = [ "../../../rtc_base/system:rtc_export" ]
   absl_deps = [ "//third_party/abseil-cpp/absl/types:optional" ]
   defines = []
   if (rtc_opus_variable_complexity) {
@@ -35,6 +33,7 @@ rtc_library("audio_encoder_opus_config") {
 rtc_source_set("audio_decoder_opus_config") {
   visibility = [ "*" ]
   sources = [ "audio_decoder_multi_channel_opus_config.h" ]
+  deps = [ "..:audio_codecs_api" ]
 }
 
 rtc_library("audio_encoder_opus") {

api/audio_codecs/opus/audio_decoder_multi_channel_opus_config.h

@@ -13,6 +13,8 @@
 
 #include <vector>
 
+#include "api/audio_codecs/audio_decoder.h"
+
 namespace webrtc {
 struct AudioDecoderMultiChannelOpusConfig {
   // The number of channels that the decoder will output.