Convert more FWL objects over to Oilpan GC.

In turn, some CFXA objects above them need to become GC'd too in
order to avoid cycles back through Persistent<>.

-- Fix some headers/IWYU to make msvc happy.

Bug: pdfium:1563
Change-Id: Ib238be056c908e96cbd04104520778740f6a9b0f
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/73210
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/xfa/fwl/cfwl_barcode.h b/xfa/fwl/cfwl_barcode.h
index 5f3c4c4..0af87fd 100644
--- a/xfa/fwl/cfwl_barcode.h
+++ b/xfa/fwl/cfwl_barcode.h
@@ -66,7 +66,7 @@
     kEncodeSuccess,
   };
 
-  explicit CFWL_Barcode(const CFWL_App* pApp);
+  explicit CFWL_Barcode(CFWL_App* pApp);
 
   void GenerateBarcodeImageCache();
   void CreateBarcodeEngine();