Make code compile with clang_use_chrome_plugin (part III)

xfa/fxbarcode/datamatrix/BC_Base256Encoder.h

Index: xfa/fxbarcode/datamatrix/BC_Base256Encoder.h
diff --git a/xfa/fxbarcode/datamatrix/BC_Base256Encoder.h b/xfa/fxbarcode/datamatrix/BC_Base256Encoder.h
index 64dbdc7ba433968e4ac8e4ebe1fcd2903dd06c5d..c41c79db081df773215be2b6fd6d24772527b118 100644
--- a/xfa/fxbarcode/datamatrix/BC_Base256Encoder.h
+++ b/xfa/fxbarcode/datamatrix/BC_Base256Encoder.h
@@ -12,9 +12,11 @@
 class CBC_Base256Encoder : public CBC_Encoder {
  public:
   CBC_Base256Encoder();
-  virtual ~CBC_Base256Encoder();
-  int32_t getEncodingMode();
-  void Encode(CBC_EncoderContext& context, int32_t& e);
+  ~CBC_Base256Encoder() override;
+
+  // CBC_Encoder
+  int32_t getEncodingMode() override;
+  void Encode(CBC_EncoderContext& context, int32_t& e) override;
 
  private:
   static FX_WCHAR randomize255State(FX_WCHAR ch, int32_t codewordPosition);