This QUIC change includes:

net/quic/core/quic_headers_stream.cc

Index: net/quic/core/quic_headers_stream.cc
diff --git a/net/quic/core/quic_headers_stream.cc b/net/quic/core/quic_headers_stream.cc
index 38e3ff48f3aa35f0be65b83ecde37be1b1713e13..b6dfec1c24641d87b907315a11277f01ee04f86e 100644
--- a/net/quic/core/quic_headers_stream.cc
+++ b/net/quic/core/quic_headers_stream.cc
@@ -9,6 +9,20 @@
 
 namespace net {
 
+QuicHeadersStream::CompressedHeaderInfo::CompressedHeaderInfo(
+    QuicStreamOffset headers_stream_offset,
+    QuicStreamOffset full_length,
+    QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener)
+    : headers_stream_offset(headers_stream_offset),
+      full_length(full_length),
+      unacked_length(full_length),
+      ack_listener(std::move(ack_listener)) {}
+
+QuicHeadersStream::CompressedHeaderInfo::CompressedHeaderInfo(
+    const CompressedHeaderInfo& other) = default;
+
+QuicHeadersStream::CompressedHeaderInfo::~CompressedHeaderInfo() {}
+
 QuicHeadersStream::QuicHeadersStream(QuicSpdySession* session)
     : QuicStream(kHeadersStreamId, session), spdy_session_(session) {
   // The headers stream is exempt from connection level flow control.
@@ -43,4 +57,95 @@ void QuicHeadersStream::MaybeReleaseSequencerBuffer() {
   }
 }
 
+QuicConsumedData QuicHeadersStream::WritevDataInner(
+    QuicIOVector iov,
+    QuicStreamOffset offset,
+    bool fin,
+    QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener) {
+  if (!session()->use_stream_notifier()) {
+    return QuicStream::WritevDataInner(iov, offset, fin,
+                                       std::move(ack_listener));
+  }
+  QuicConsumedData consumed =
+      QuicStream::WritevDataInner(iov, offset, fin, nullptr);
+  if (consumed.bytes_consumed == 0 || ack_listener == nullptr) {
+    // No need to update unacked_headers_ if no byte is consumed or there is no
+    // ack listener.
+    return consumed;
+  }
+
+  if (!unacked_headers_.empty() &&
+      (offset == unacked_headers_.back().headers_stream_offset +
+                     unacked_headers_.back().full_length) &&
+      ack_listener == unacked_headers_.back().ack_listener) {
+    // Try to combine with latest inserted entry if they belong to the same
+    // header (i.e., having contiguous offset and the same ack listener).
+    unacked_headers_.back().full_length += consumed.bytes_consumed;
+    unacked_headers_.back().unacked_length += consumed.bytes_consumed;
+  } else {
+    unacked_headers_.push_back(CompressedHeaderInfo(
+        offset, consumed.bytes_consumed, std::move(ack_listener)));
+  }
+  return consumed;
+}
+
+void QuicHeadersStream::OnStreamFrameAcked(const QuicStreamFrame& frame,
+                                           QuicTime::Delta ack_delay_time) {
+  for (CompressedHeaderInfo& header : unacked_headers_) {
+    if (frame.offset < header.headers_stream_offset) {
+      // This header frame offset belongs to headers with smaller offset, stop
+      // processing.
+      break;
+    }
+
+    if (frame.offset >= header.headers_stream_offset + header.full_length) {
+      // This header frame belongs to headers with larger offset.
+      continue;
+    }
+
+    if (header.unacked_length < frame.data_length) {
+      // This header frame is out of range.
+      CloseConnectionWithDetails(QUIC_INTERNAL_ERROR,
+                                 "Unsent stream data is acked");
+      return;
+    }
+
+    header.unacked_length -= frame.data_length;
+
+    if (header.ack_listener != nullptr) {
+      header.ack_listener->OnPacketAcked(frame.data_length, ack_delay_time);
+    }
+    break;
+  }
+
+  // Remove headers which are fully acked. Please note, header frames can be
+  // acked out of order, but unacked_headers_ is cleaned up in order.
+  while (!unacked_headers_.empty() &&
+         unacked_headers_.front().unacked_length == 0) {
+    unacked_headers_.pop_front();
+  }
+  QuicStream::OnStreamFrameAcked(frame, ack_delay_time);
+}
+
+void QuicHeadersStream::OnStreamFrameRetransmitted(
+    const QuicStreamFrame& frame) {
+  for (CompressedHeaderInfo& header : unacked_headers_) {
+    if (frame.offset < header.headers_stream_offset) {
+      // This header frame offset belongs to headers with smaller offset, stop
+      // processing.
+      break;
+    }
+
+    if (frame.offset >= header.headers_stream_offset + header.full_length) {
+      // This header frame belongs to headers with larger offset.
+      continue;
+    }
+
+    if (header.ack_listener != nullptr) {
+      header.ack_listener->OnPacketRetransmitted(frame.data_length);
+    }
+    break;
+  }
+}
+
 }  // namespace net