chrome: Replace base::Optional and friends with absl counterparts

This replaces:
- base::Optional -> absl::optional
- include "base/optional.h"
  ->
  include "third_party/abseil-cpp/absl/types/optional.h"
- base::nullopt -> absl::nullopt
- base::make_optional -> absl::make_optional

Bug: 1202909
AX-Relnotes: n/a.
Change-Id: If011b89bfb5f3561e152aeee242b0b2fe1ab4587
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2897520
Auto-Submit: Anton Bikineev <[email protected]>
Commit-Queue: Peter Kasting <[email protected]>
Reviewed-by: Peter Kasting <[email protected]>
Owners-Override: Peter Kasting <[email protected]>
Cr-Commit-Position: refs/heads/master@{#883266}
diff --git a/chrome/browser/web_applications/web_app_proto_utils.h b/chrome/browser/web_applications/web_app_proto_utils.h
index 4546b8a..bdab41df 100644
--- a/chrome/browser/web_applications/web_app_proto_utils.h
+++ b/chrome/browser/web_applications/web_app_proto_utils.h
@@ -7,10 +7,10 @@
 
 #include <vector>
 
-#include "base/optional.h"
 #include "chrome/browser/web_applications/proto/web_app.pb.h"
 #include "chrome/browser/web_applications/web_app.h"
 #include "components/sync/protocol/web_app_specifics.pb.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
 
 namespace web_app {
 
@@ -19,7 +19,7 @@
 using RepeatedIconInfosProto =
     const ::google::protobuf::RepeatedPtrField<::sync_pb::WebAppIconInfo>;
 
-base::Optional<std::vector<WebApplicationIconInfo>> ParseWebAppIconInfos(
+absl::optional<std::vector<WebApplicationIconInfo>> ParseWebAppIconInfos(
     const char* container_name_for_logging,
     RepeatedIconInfosProto icon_infos_proto);
 
@@ -30,7 +30,7 @@
 sync_pb::WebAppIconInfo WebAppIconInfoToSyncProto(
     const WebApplicationIconInfo& icon_info);
 
-base::Optional<WebApp::SyncFallbackData> ParseSyncFallbackDataStruct(
+absl::optional<WebApp::SyncFallbackData> ParseSyncFallbackDataStruct(
     const sync_pb::WebAppSpecifics& sync_proto);
 
 ::sync_pb::WebAppSpecifics::UserDisplayMode ToWebAppSpecificsUserDisplayMode(