gfe-relnote: (n/a) Change SetQuicFlag to take the flag variable directly instead of a pointer to it. Refactor for Envoy integration, no behavior change.

This is needed for Envoy integration because the current syntax(SetQuicFlag(&FLAG_foo)) requires FLAG_foo is a valid c++ identifier, which is not the case in Envoy.

PiperOrigin-RevId: 246196929
Change-Id: I7d56b23f0fa51fcdd17acc0837508710316a6826
diff --git a/quic/core/quic_stream_send_buffer_test.cc b/quic/core/quic_stream_send_buffer_test.cc
index 57e2bd1..3a5efb5 100644
--- a/quic/core/quic_stream_send_buffer_test.cc
+++ b/quic/core/quic_stream_send_buffer_test.cc
@@ -48,7 +48,7 @@
               QuicStreamSendBufferPeer::CurrentWriteSlice(&send_buffer_));
 
     // Save all data.
-    SetQuicFlag(&FLAGS_quic_send_buffer_max_data_slice_size, 1024);
+    SetQuicFlag(FLAGS_quic_send_buffer_max_data_slice_size, 1024);
     send_buffer_.SaveStreamData(iov, 2, 0, 2048);
     send_buffer_.SaveMemSlice(std::move(slice1));
     EXPECT_TRUE(slice1.empty());