Pass CFX_Matrix by const-ref in fxbarcode/

-- Comment one suspicious line while at it.

Change-Id: I67385abcd88f1ffccca4e12517806865e04f75d0
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/79350
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fxbarcode/cbc_code128.h b/fxbarcode/cbc_code128.h
index 2ccf07d..04a05b5 100644
--- a/fxbarcode/cbc_code128.h
+++ b/fxbarcode/cbc_code128.h
@@ -22,7 +22,7 @@
   BC_TYPE GetType() override;
   bool Encode(WideStringView contents) override;
   bool RenderDevice(CFX_RenderDevice* device,
-                    const CFX_Matrix* matrix) override;
+                    const CFX_Matrix& matrix) override;
 
  private:
   CBC_OnedCode128Writer* GetOnedCode128Writer();