Remove unused set_endianness from QuicDataReader.

gfe-relnote: n/a (Remove dead code)
PiperOrigin-RevId: 281415125
Change-Id: Ia279d063545fb6e5575fa558a9178094a837d9ef

quic/core/quic_data_reader.h

diff --git a/quic/core/quic_data_reader.h b/quic/core/quic_data_reader.h
index a8b6521..acd30fd 100644
--- a/quic/core/quic_data_reader.h
+++ b/quic/core/quic_data_reader.h
@@ -154,10 +154,6 @@
   // DOES NOT forward the internal iterator.
   uint8_t PeekByte() const;
 
-  void set_endianness(quiche::Endianness endianness) {
-    endianness_ = endianness;
-  }
-
   // Read an IETF-encoded Variable Length Integer and place the result
   // in |*result|.
   // Returns true if it works, false if not. The only error is that