In QUIC, send data is copied to streams rather than frames. Protected by FLAGS_quic_reloadable_flag…

net/quic/core/frames/quic_stream_frame.h

Index: net/quic/core/frames/quic_stream_frame.h
diff --git a/net/quic/core/frames/quic_stream_frame.h b/net/quic/core/frames/quic_stream_frame.h
index 138cc4831723880eec53b9f2a7fb4b05eb07d82a..90cfbfe8d2ce1f7e7308b0576c78ea1191f246fe 100644
--- a/net/quic/core/frames/quic_stream_frame.h
+++ b/net/quic/core/frames/quic_stream_frame.h
@@ -50,6 +50,10 @@ struct QUIC_EXPORT_PRIVATE QuicStreamFrame {
                   QuicStreamOffset offset,
                   QuicPacketLength data_length,
                   UniqueStreamBuffer buffer);
+  QuicStreamFrame(QuicStreamId stream_id,
+                  bool fin,
+                  QuicStreamOffset offset,
+                  QuicPacketLength data_length);
   ~QuicStreamFrame();
 
   friend QUIC_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os,
@@ -60,6 +64,10 @@ struct QUIC_EXPORT_PRIVATE QuicStreamFrame {
   QuicPacketLength data_length;
   const char* data_buffer;
   QuicStreamOffset offset;  // Location of this data in the stream.
+  // TODO(fayang): When deprecating
+  // FLAGS_quic_reloadable_flag_quic_stream_owns_data: (1) Remove buffer from
+  // QuicStreamFrame; (2) remove the constructor uses UniqueStreamBuffer and (3)
+  // Move definition of UniqueStreamBuffer to QuicStreamSendBuffer.
   // nullptr when the QuicStreamFrame is received, and non-null when sent.
   UniqueStreamBuffer buffer;