Remove third_party/base/optional.h.

Replace with absl everywhere.

Bug: pdfium:1726
Change-Id: I08118cd765626a0703a0692c812872915594c370
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/85519
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/xfa/fwl/cfwl_barcode.h b/xfa/fwl/cfwl_barcode.h
index 82020ba..23266a9 100644
--- a/xfa/fwl/cfwl_barcode.h
+++ b/xfa/fwl/cfwl_barcode.h
@@ -12,7 +12,7 @@
 #include <memory>
 
 #include "fxbarcode/BC_Library.h"
-#include "third_party/base/optional.h"
+#include "third_party/abseil-cpp/absl/types/optional.h"
 #include "xfa/fwl/cfwl_edit.h"
 
 class CFX_Barcode;