Make code compile with clang_use_chrome_plugin (part III)

This change contains files in xfa/fxbarcode directory.
This is part of the efforts to make PDFium code compilable
by Clang chromium style plugins.

The changes are mainly the following:
-- move inline constructor/destructor of complex class/struct out-of-line;
-- add constructor/destructor of complex class/struct if not
 explicitly defined;
-- add explicit out-of-line copy constructor when needed;
-- move inline virtual functions out-of-line;
-- Properly mark virtual functions with 'override';
-- some minor cleanups;

BUG=pdfium:469

Review-Url: https://codereview.chromium.org/2067903002

1 files changed, 7 insertions, 3 deletions

diff --git a/xfa/fxbarcode/datamatrix/BC_DataMatrixReader.h b/xfa/fxbarcode/datamatrix/BC_DataMatrixReader.h
index 21fc54eeb5..c7a0995dcb 100644
--- a/xfa/fxbarcode/datamatrix/BC_DataMatrixReader.h
+++ b/xfa/fxbarcode/datamatrix/BC_DataMatrixReader.h
@@ -15,9 +15,13 @@ class CBC_DataMatrixDecoder;
 class CBC_DataMatrixReader : public CBC_Reader {
  public:
   CBC_DataMatrixReader();
-  virtual ~CBC_DataMatrixReader();
-  CFX_ByteString Decode(CBC_BinaryBitmap* image, int32_t& e);
-  CFX_ByteString Decode(CBC_BinaryBitmap* image, int hints, int32_t& e);
+  ~CBC_DataMatrixReader() override;
+
+  // CBC_Reader
+  CFX_ByteString Decode(CBC_BinaryBitmap* image, int32_t& e) override;
+  CFX_ByteString Decode(CBC_BinaryBitmap* image,
+                        int hints,
+                        int32_t& e) override;
 
   virtual void Init();