Use std::optional in //content/browser/aggregation_service

I generated these changes with the following commands:

  cd content/browser/aggregation_service/
  git sed absl::nullopt std::nullopt
  git sed absl::optional std::optional
  git sed '"third_party/abseil-cpp/absl/types/optional.h"' '<optional>'
  git cl format

This was not entirely automatic, as I had to manually move '#include
<optional>' into the correct block of includes.

Bug: 1503962
Low-Coverage-Reason: TRIVIAL_CHANGE
Change-Id: I4d7a89bfc5507e2dff395a85fead41a77c47f0d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5047250
Auto-Submit: Dan McArdle <dmcardle@chromium.org>
Commit-Queue: Nan Lin <linnan@chromium.org>
Reviewed-by: Andrew Paseltiner <apaseltiner@chromium.org>
Reviewed-by: Nan Lin <linnan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1227578}

diff --git a/content/browser/aggregation_service/report_scheduler_timer.h b/content/browser/aggregation_service/report_scheduler_timer.h
index 640d863..2e8fd720 100644
--- a/content/browser/aggregation_service/report_scheduler_timer.h
+++ b/content/browser/aggregation_service/report_scheduler_timer.h

@@ -6,6 +6,7 @@
 #define CONTENT_BROWSER_AGGREGATION_SERVICE_REPORT_SCHEDULER_TIMER_H_
 
 #include <memory>
+#include <optional>
 
 #include "base/functional/callback_forward.h"
 #include "base/memory/weak_ptr.h"
@@ -16,7 +17,6 @@
 #include "content/common/content_export.h"
 #include "services/network/public/cpp/network_connection_tracker.h"
 #include "services/network/public/mojom/network_change_manager.mojom.h"
-#include "third_party/abseil-cpp/absl/types/optional.h"
 
 namespace base {
 class Time;
@@ -39,9 +39,9 @@
 
     // Should be overridden with a method that gets the next report time that
     // the timer should fire at and returns it via the callback. If there is no
-    // next report time, `absl::nullopt` should be returned instead.
+    // next report time, `std::nullopt` should be returned instead.
     virtual void GetNextReportTime(
-        base::OnceCallback<void(absl::optional<base::Time>)>,
+        base::OnceCallback<void(std::optional<base::Time>)>,
         base::Time now) = 0;
 
     // Called when the timer is fired, with the current time `now`. `Refresh()`
@@ -61,7 +61,7 @@
     // the given argument; this may be necessary after the report times were
     // adjusted.
     virtual void AdjustOfflineReportTimes(
-        base::OnceCallback<void(absl::optional<base::Time>)>) = 0;
+        base::OnceCallback<void(std::optional<base::Time>)>) = 0;
   };
 
   explicit ReportSchedulerTimer(std::unique_ptr<Delegate> delegate);
@@ -77,7 +77,7 @@
 
   // Schedules `reporting_time_reached_timer_` to fire at that time, unless the
   // timer is already set to fire earlier.
-  void MaybeSet(absl::optional<base::Time> reporting_time);
+  void MaybeSet(std::optional<base::Time> reporting_time);
 
  private:
   void OnTimerFired();