Remove useless CBC_SymbolShapeHint.

Mark some methods as virtual/override in formerly CBC_SymbolShapeHint
derived classes.

Change-Id: Ia6d83e0b2c63c8fb440bc1d5beb258a796e1d42f
Reviewed-on: https://pdfium-review.googlesource.com/5738
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/fxbarcode/datamatrix/BC_DataMatrixSymbolInfo144.cpp b/fxbarcode/datamatrix/BC_DataMatrixSymbolInfo144.cpp
index c0994af..1229321 100644
--- a/fxbarcode/datamatrix/BC_DataMatrixSymbolInfo144.cpp
+++ b/fxbarcode/datamatrix/BC_DataMatrixSymbolInfo144.cpp
@@ -30,7 +30,7 @@
 
 CBC_DataMatrixSymbolInfo144::~CBC_DataMatrixSymbolInfo144() {}
 
-int32_t CBC_DataMatrixSymbolInfo144::getInterleavedBlockCount() {
+int32_t CBC_DataMatrixSymbolInfo144::getInterleavedBlockCount() const {
   return 10;
 }