Migrate absl::optional to std::optional

Bug: webrtc:342905193
No-Try: True
Change-Id: Icc968be43b8830038ea9a1f5f604307220457807
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/361021
Auto-Submit: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42911}
diff --git a/test/function_audio_decoder_factory.h b/test/function_audio_decoder_factory.h
index 2848ce8..c314249 100644
--- a/test/function_audio_decoder_factory.h
+++ b/test/function_audio_decoder_factory.h
@@ -32,14 +32,14 @@
       std::function<std::unique_ptr<AudioDecoder>()> create)
       : create_([create](const Environment&,
                          const SdpAudioFormat&,
-                         absl::optional<AudioCodecPairId> codec_pair_id) {
+                         std::optional<AudioCodecPairId> codec_pair_id) {
           return create();
         }) {}
   explicit FunctionAudioDecoderFactory(
       std::function<std::unique_ptr<AudioDecoder>(
           const Environment&,
           const SdpAudioFormat&,
-          absl::optional<AudioCodecPairId> codec_pair_id)> create)
+          std::optional<AudioCodecPairId> codec_pair_id)> create)
       : create_(std::move(create)) {}
 
   // Unused by tests.
@@ -55,7 +55,7 @@
   std::unique_ptr<AudioDecoder> Create(
       const Environment& env,
       const SdpAudioFormat& format,
-      absl::optional<AudioCodecPairId> codec_pair_id) override {
+      std::optional<AudioCodecPairId> codec_pair_id) override {
     return create_(env, format, codec_pair_id);
   }
 
@@ -63,7 +63,7 @@
   const std::function<std::unique_ptr<AudioDecoder>(
       const Environment&,
       const SdpAudioFormat&,
-      absl::optional<AudioCodecPairId> codec_pair_id)>
+      std::optional<AudioCodecPairId> codec_pair_id)>
       create_;
 };