In QUIC v39, read and write integers and floating numbers in big endian.

net/quic/core/quic_data_reader.h

Index: net/quic/core/quic_data_reader.h
diff --git a/net/quic/core/quic_data_reader.h b/net/quic/core/quic_data_reader.h
index a4dc1a928808839d3c5c54fbc9167dd77d2b0fc3..755f2fcc66fa5c4b25cfc3bf2510b6572589a823 100644
--- a/net/quic/core/quic_data_reader.h
+++ b/net/quic/core/quic_data_reader.h
@@ -125,6 +125,8 @@ class QUIC_EXPORT_PRIVATE QuicDataReader {
   // DOES NOT forward the internal iterator.
   uint8_t PeekByte() const;
 
+  void set_endianness(Endianness endianness) { endianness_ = endianness; }
+
  private:
   // Returns true if the underlying buffer has enough room to read the given
   // amount of bytes.