Make Quic client more memory efficient. Protected by --quic_headers_stream_release_sequencer_buffer.

net/quic/core/quic_client_session_base.cc

Index: net/quic/core/quic_client_session_base.cc
diff --git a/net/quic/core/quic_client_session_base.cc b/net/quic/core/quic_client_session_base.cc
index 3fb43d14b14ba05e4a11b513c2ed3a325b76a44f..35438af5f0e15a61f0f7e899ac510162df9180b5 100644
--- a/net/quic/core/quic_client_session_base.cc
+++ b/net/quic/core/quic_client_session_base.cc
@@ -188,6 +188,7 @@ void QuicClientSessionBase::DeletePromised(QuicClientPromisedInfo* promised) {
   // Since promised_by_id_ contains the unique_ptr, this will destroy
   // promised.
   promised_by_id_.erase(promised->id());
+  headers_stream()->MaybeReleaseSequencerBuffer();
 }
 
 void QuicClientSessionBase::OnPushStreamTimedOut(QuicStreamId stream_id) {}
@@ -201,4 +202,14 @@ void QuicClientSessionBase::ResetPromised(QuicStreamId id,
   }
 }
 
+void QuicClientSessionBase::CloseStreamInner(QuicStreamId stream_id,
+                                             bool locally_reset) {
+  QuicSpdySession::CloseStreamInner(stream_id, locally_reset);
+  headers_stream()->MaybeReleaseSequencerBuffer();
+}
+
+bool QuicClientSessionBase::ShouldReleaseHeadersStreamSequencerBuffer() {
+  return num_active_requests() == 0 && promised_by_id_.empty();
+}
+
 }  // namespace net