gfe-relnote: (n/a) Use QuicIntervalSet::AddOptimizedForAppend in
QuicStreamSendBuffer to optimize sequentially acked ranges. No behavior change,
not protected.

PiperOrigin-RevId: 301903837
Change-Id: I5e628a628d7a6100b7f31fac2238bb1d3445d149

quic/core/quic_stream_send_buffer.cc

diff --git a/quic/core/quic_stream_send_buffer.cc b/quic/core/quic_stream_send_buffer.cc
index 8c31be8..7b8a23b 100644
--- a/quic/core/quic_stream_send_buffer.cc
+++ b/quic/core/quic_stream_send_buffer.cc
@@ -149,7 +149,7 @@
     if (stream_bytes_outstanding_ < data_length) {
       return false;
     }
-    bytes_acked_.Add(offset, offset + data_length);
+    bytes_acked_.AddOptimizedForAppend(offset, offset + data_length);
     *newly_acked_length = data_length;
     stream_bytes_outstanding_ -= data_length;
     pending_retransmissions_.Difference(offset, offset + data_length);