Replace rtc::Optional with absl::optional in modules/audio processing

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

This CL generated by running script with parameter 'modules/audio_processing'

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: Id29f8de59dba704787c2c38a3d05c60827c181b0
Reviewed-on: https://webrtc-review.googlesource.com/83982
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23653}

modules/audio_processing/aec3/render_delay_controller.h

@@ -11,9 +11,9 @@
 #ifndef MODULES_AUDIO_PROCESSING_AEC3_RENDER_DELAY_CONTROLLER_H_
 #define MODULES_AUDIO_PROCESSING_AEC3_RENDER_DELAY_CONTROLLER_H_
 
+#include "absl/types/optional.h"
 #include "api/array_view.h"
 #include "api/audio/echo_canceller3_config.h"
-#include "api/optional.h"
 #include "modules/audio_processing/aec3/delay_estimate.h"
 #include "modules/audio_processing/aec3/downsampled_render_buffer.h"
 #include "modules/audio_processing/aec3/render_delay_buffer.h"
@@ -36,10 +36,10 @@ class RenderDelayController {
   virtual void LogRenderCall() = 0;
 
   // Aligns the render buffer content with the capture signal.
-  virtual rtc::Optional<DelayEstimate> GetDelay(
+  virtual absl::optional<DelayEstimate> GetDelay(
       const DownsampledRenderBuffer& render_buffer,
       size_t render_delay_buffer_delay,
-      const rtc::Optional<int>& echo_remover_delay,
+      const absl::optional<int>& echo_remover_delay,
       rtc::ArrayView<const float> capture) = 0;
 };
 }  // namespace webrtc