Replace rtc::Optional with absl::optional in media, ortc, p2p

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

This CL generated by running script with parameters 'media ortc p2p':
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: I19167714af7cc1436d34cfcba6c8b3718d8e677b
Reviewed-on: https://webrtc-review.googlesource.com/83731
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23638}
diff --git a/ortc/rtpparametersconversion.cc b/ortc/rtpparametersconversion.cc
index 1c336e2..ff5bece 100644
--- a/ortc/rtpparametersconversion.cc
+++ b/ortc/rtpparametersconversion.cc
@@ -230,7 +230,7 @@
   return std::move(cricket_streams);
 }
 
-rtc::Optional<RtcpFeedback> ToRtcpFeedback(
+absl::optional<RtcpFeedback> ToRtcpFeedback(
     const cricket::FeedbackParam& cricket_feedback) {
   if (cricket_feedback.id() == cricket::kRtcpFbParamCcm) {
     if (cricket_feedback.param() == cricket::kRtcpFbCcmParamFir) {
@@ -238,7 +238,7 @@
     } else {
       RTC_LOG(LS_WARNING) << "Unsupported parameter for CCM RTCP feedback: "
                           << cricket_feedback.param();
-      return rtc::nullopt;
+      return absl::nullopt;
     }
   } else if (cricket_feedback.id() == cricket::kRtcpFbParamNack) {
     if (cricket_feedback.param().empty()) {
@@ -249,13 +249,13 @@
     } else {
       RTC_LOG(LS_WARNING) << "Unsupported parameter for NACK RTCP feedback: "
                           << cricket_feedback.param();
-      return rtc::nullopt;
+      return absl::nullopt;
     }
   } else if (cricket_feedback.id() == cricket::kRtcpFbParamRemb) {
     if (!cricket_feedback.param().empty()) {
       RTC_LOG(LS_WARNING) << "Unsupported parameter for REMB RTCP feedback: "
                           << cricket_feedback.param();
-      return rtc::nullopt;
+      return absl::nullopt;
     } else {
       return RtcpFeedback(RtcpFeedbackType::REMB);
     }
@@ -264,14 +264,14 @@
       RTC_LOG(LS_WARNING)
           << "Unsupported parameter for transport-cc RTCP feedback: "
           << cricket_feedback.param();
-      return rtc::nullopt;
+      return absl::nullopt;
     } else {
       return RtcpFeedback(RtcpFeedbackType::TRANSPORT_CC);
     }
   }
   RTC_LOG(LS_WARNING) << "Unsupported RTCP feedback type: "
                       << cricket_feedback.id();
-  return rtc::nullopt;
+  return absl::nullopt;
 }
 
 std::vector<RtpEncodingParameters> ToRtpEncodings(
@@ -328,7 +328,7 @@
   codec.preferred_payload_type.emplace(cricket_codec.id);
   for (const cricket::FeedbackParam& cricket_feedback :
        cricket_codec.feedback_params.params()) {
-    rtc::Optional<RtcpFeedback> feedback = ToRtcpFeedback(cricket_feedback);
+    absl::optional<RtcpFeedback> feedback = ToRtcpFeedback(cricket_feedback);
     if (feedback) {
       codec.rtcp_feedback.push_back(feedback.value());
     }
@@ -368,7 +368,7 @@
   codec_param.payload_type = cricket_codec.id;
   for (const cricket::FeedbackParam& cricket_feedback :
        cricket_codec.feedback_params.params()) {
-    rtc::Optional<RtcpFeedback> feedback = ToRtcpFeedback(cricket_feedback);
+    absl::optional<RtcpFeedback> feedback = ToRtcpFeedback(cricket_feedback);
     if (feedback) {
       codec_param.rtcp_feedback.push_back(feedback.value());
     }