Replace rtc::Optional with absl::optional in api

This is a no-op change because rtc::Optional is an alias to absl::optional

This CL generated by running script with parameter 'api'
Then undo changes to optional target itself and optional_unittests

find $@ -type f \( -name \*.h -o -name \*.cc \) \
-exec sed -i 's|rtc::Optional|absl::optional|g' {} \+ \
-exec sed -i 's|rtc::nullopt|absl::nullopt|g' {} \+ \
-exec sed -i 's|#include "api/optional.h"|#include "absl/types/optional.h"|' {} \+

find $@ -type f -name BUILD.gn \
-exec sed -r -i 's|"[\./api]*:optional"|"//third_party/abseil-cpp/absl/types:optional"|' {} \+;

git cl format

Bug: webrtc:9078
Change-Id: I44093da213369d6a502e33792c694f620f53b779
Reviewed-on: https://webrtc-review.googlesource.com/84621
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23707}
diff --git a/api/audio_codecs/opus/BUILD.gn b/api/audio_codecs/opus/BUILD.gn
index d235d1a..953482e 100644
--- a/api/audio_codecs/opus/BUILD.gn
+++ b/api/audio_codecs/opus/BUILD.gn
@@ -19,8 +19,8 @@
     "audio_encoder_opus_config.h",
   ]
   deps = [
-    "../..:optional",
     "../../../rtc_base:rtc_base_approved",
+    "//third_party/abseil-cpp/absl/types:optional",
   ]
   defines = []
   if (rtc_opus_variable_complexity) {
@@ -42,9 +42,9 @@
   deps = [
     ":audio_encoder_opus_config",
     "..:audio_codecs_api",
-    "../..:optional",
     "../../../modules/audio_coding:webrtc_opus",
     "../../../rtc_base:rtc_base_approved",
+    "//third_party/abseil-cpp/absl/types:optional",
   ]
 }
 
@@ -57,9 +57,9 @@
   ]
   deps = [
     "..:audio_codecs_api",
-    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:webrtc_opus",
     "../../../rtc_base:rtc_base_approved",
+    "//third_party/abseil-cpp/absl/types:optional",
   ]
 }
diff --git a/api/audio_codecs/opus/audio_decoder_opus.cc b/api/audio_codecs/opus/audio_decoder_opus.cc
index 73a0a3f..81bee77 100644
--- a/api/audio_codecs/opus/audio_decoder_opus.cc
+++ b/api/audio_codecs/opus/audio_decoder_opus.cc
@@ -20,9 +20,9 @@
 
 namespace webrtc {
 
-rtc::Optional<AudioDecoderOpus::Config> AudioDecoderOpus::SdpToConfig(
+absl::optional<AudioDecoderOpus::Config> AudioDecoderOpus::SdpToConfig(
     const SdpAudioFormat& format) {
-  const auto num_channels = [&]() -> rtc::Optional<int> {
+  const auto num_channels = [&]() -> absl::optional<int> {
     auto stereo = format.parameters.find("stereo");
     if (stereo != format.parameters.end()) {
       if (stereo->second == "0") {
@@ -30,7 +30,7 @@
       } else if (stereo->second == "1") {
         return 2;
       } else {
-        return rtc::nullopt;  // Bad stereo parameter.
+        return absl::nullopt;  // Bad stereo parameter.
       }
     }
     return 1;  // Default to mono.
@@ -40,7 +40,7 @@
       num_channels) {
     return Config{*num_channels};
   } else {
-    return rtc::nullopt;
+    return absl::nullopt;
   }
 }
 
@@ -56,7 +56,7 @@
 
 std::unique_ptr<AudioDecoder> AudioDecoderOpus::MakeAudioDecoder(
     Config config,
-    rtc::Optional<AudioCodecPairId> /*codec_pair_id*/) {
+    absl::optional<AudioCodecPairId> /*codec_pair_id*/) {
   return rtc::MakeUnique<AudioDecoderOpusImpl>(config.num_channels);
 }
 
diff --git a/api/audio_codecs/opus/audio_decoder_opus.h b/api/audio_codecs/opus/audio_decoder_opus.h
index f76d244..de26026 100644
--- a/api/audio_codecs/opus/audio_decoder_opus.h
+++ b/api/audio_codecs/opus/audio_decoder_opus.h
@@ -14,10 +14,10 @@
 #include <memory>
 #include <vector>
 
+#include "absl/types/optional.h"
 #include "api/audio_codecs/audio_codec_pair_id.h"
 #include "api/audio_codecs/audio_decoder.h"
 #include "api/audio_codecs/audio_format.h"
-#include "api/optional.h"
 
 namespace webrtc {
 
@@ -29,11 +29,11 @@
   struct Config {
     int num_channels;
   };
-  static rtc::Optional<Config> SdpToConfig(const SdpAudioFormat& audio_format);
+  static absl::optional<Config> SdpToConfig(const SdpAudioFormat& audio_format);
   static void AppendSupportedDecoders(std::vector<AudioCodecSpec>* specs);
   static std::unique_ptr<AudioDecoder> MakeAudioDecoder(
       Config config,
-      rtc::Optional<AudioCodecPairId> codec_pair_id = rtc::nullopt);
+      absl::optional<AudioCodecPairId> codec_pair_id = absl::nullopt);
 };
 
 }  // namespace webrtc
diff --git a/api/audio_codecs/opus/audio_encoder_opus.cc b/api/audio_codecs/opus/audio_encoder_opus.cc
index 8ba66fb..36d82b3 100644
--- a/api/audio_codecs/opus/audio_encoder_opus.cc
+++ b/api/audio_codecs/opus/audio_encoder_opus.cc
@@ -14,7 +14,7 @@
 
 namespace webrtc {
 
-rtc::Optional<AudioEncoderOpusConfig> AudioEncoderOpus::SdpToConfig(
+absl::optional<AudioEncoderOpusConfig> AudioEncoderOpus::SdpToConfig(
     const SdpAudioFormat& format) {
   return AudioEncoderOpusImpl::SdpToConfig(format);
 }
@@ -32,7 +32,7 @@
 std::unique_ptr<AudioEncoder> AudioEncoderOpus::MakeAudioEncoder(
     const AudioEncoderOpusConfig& config,
     int payload_type,
-    rtc::Optional<AudioCodecPairId> /*codec_pair_id*/) {
+    absl::optional<AudioCodecPairId> /*codec_pair_id*/) {
   return AudioEncoderOpusImpl::MakeAudioEncoder(config, payload_type);
 }
 
diff --git a/api/audio_codecs/opus/audio_encoder_opus.h b/api/audio_codecs/opus/audio_encoder_opus.h
index 6325269..20aaaf7 100644
--- a/api/audio_codecs/opus/audio_encoder_opus.h
+++ b/api/audio_codecs/opus/audio_encoder_opus.h
@@ -14,11 +14,11 @@
 #include <memory>
 #include <vector>
 
+#include "absl/types/optional.h"
 #include "api/audio_codecs/audio_codec_pair_id.h"
 #include "api/audio_codecs/audio_encoder.h"
 #include "api/audio_codecs/audio_format.h"
 #include "api/audio_codecs/opus/audio_encoder_opus_config.h"
-#include "api/optional.h"
 
 namespace webrtc {
 
@@ -28,14 +28,14 @@
 // NOTE: This struct is still under development and may change without notice.
 struct AudioEncoderOpus {
   using Config = AudioEncoderOpusConfig;
-  static rtc::Optional<AudioEncoderOpusConfig> SdpToConfig(
+  static absl::optional<AudioEncoderOpusConfig> SdpToConfig(
       const SdpAudioFormat& audio_format);
   static void AppendSupportedEncoders(std::vector<AudioCodecSpec>* specs);
   static AudioCodecInfo QueryAudioEncoder(const AudioEncoderOpusConfig& config);
   static std::unique_ptr<AudioEncoder> MakeAudioEncoder(
       const AudioEncoderOpusConfig& config,
       int payload_type,
-      rtc::Optional<AudioCodecPairId> codec_pair_id = rtc::nullopt);
+      absl::optional<AudioCodecPairId> codec_pair_id = absl::nullopt);
 };
 
 }  // namespace webrtc
diff --git a/api/audio_codecs/opus/audio_encoder_opus_config.h b/api/audio_codecs/opus/audio_encoder_opus_config.h
index d586592..c7067bb 100644
--- a/api/audio_codecs/opus/audio_encoder_opus_config.h
+++ b/api/audio_codecs/opus/audio_encoder_opus_config.h
@@ -15,7 +15,7 @@
 
 #include <vector>
 
-#include "api/optional.h"
+#include "absl/types/optional.h"
 
 namespace webrtc {
 
@@ -42,7 +42,7 @@
 
   // NOTE: This member must always be set.
   // TODO(kwiberg): Turn it into just an int.
-  rtc::Optional<int> bitrate_bps;
+  absl::optional<int> bitrate_bps;
 
   bool fec_enabled;
   bool cbr_enabled;