content: 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
Change-Id: Ie9f37bcbf6115632a19f4d063387d07b3723926f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2897246
Commit-Queue: Peter Kasting <[email protected]>
Reviewed-by: Peter Kasting <[email protected]>
Owners-Override: Peter Kasting <[email protected]>
Cr-Commit-Position: refs/heads/master@{#883270}
diff --git a/content/renderer/loader/navigation_body_loader_unittest.cc b/content/renderer/loader/navigation_body_loader_unittest.cc
index 1b2517a..6dd5e80 100644
--- a/content/renderer/loader/navigation_body_loader_unittest.cc
+++ b/content/renderer/loader/navigation_body_loader_unittest.cc
@@ -98,7 +98,7 @@
       int64_t total_encoded_body_length,
       int64_t total_decoded_body_length,
       bool should_report_corb_blocking,
-      const base::Optional<blink::WebURLError>& error) override {
+      const absl::optional<blink::WebURLError>& error) override {
     ASSERT_TRUE(expecting_finished_);
     did_finish_ = true;
     error_ = error;
@@ -171,7 +171,7 @@
   bool toggle_defers_loading_ = false;
   bool destroy_loader_ = false;
   std::string data_received_;
-  base::Optional<blink::WebURLError> error_;
+  absl::optional<blink::WebURLError> error_;
 };
 
 TEST_F(NavigationBodyLoaderTest, SetDefersBeforeStart) {