Update from https://crrev.com/311076

net/quic/quic_session.cc

Index: net/quic/quic_session.cc
diff --git a/net/quic/quic_session.cc b/net/quic/quic_session.cc
index 20fd9835b0c5daa64dcaa7fd679f32f1181edf11..865af07cd0dbddbb2ecdd1c70d083c6459c381ff 100644
--- a/net/quic/quic_session.cc
+++ b/net/quic/quic_session.cc
@@ -104,20 +104,16 @@ QuicSession::QuicSession(QuicConnection* connection, const QuicConfig& config)
       next_stream_id_(is_server() ? 2 : 5),
       largest_peer_created_stream_id_(0),
       error_(QUIC_NO_ERROR),
+      flow_controller_(new QuicFlowController(
+          connection_.get(),
+          0,
+          is_server(),
+          kMinimumFlowControlSendWindow,
+          config_.GetInitialSessionFlowControlWindowToSend(),
+          config_.GetInitialSessionFlowControlWindowToSend())),
       goaway_received_(false),
       goaway_sent_(false),
       has_pending_handshake_(false) {
-  if (connection_->version() == QUIC_VERSION_19) {
-    flow_controller_.reset(new QuicFlowController(
-        connection_.get(), 0, is_server(), kMinimumFlowControlSendWindow,
-        config_.GetInitialFlowControlWindowToSend(),
-        config_.GetInitialFlowControlWindowToSend()));
-  } else {
-    flow_controller_.reset(new QuicFlowController(
-        connection_.get(), 0, is_server(), kMinimumFlowControlSendWindow,
-        config_.GetInitialSessionFlowControlWindowToSend(),
-        config_.GetInitialSessionFlowControlWindowToSend()));
-  }
 }
 
 void QuicSession::InitializeSession() {
@@ -464,7 +460,6 @@ bool QuicSession::IsCryptoHandshakeConfirmed() {
 
 void QuicSession::OnConfigNegotiated() {
   connection_->SetFromConfig(config_);
-  QuicVersion version = connection()->version();
 
   uint32 max_streams = config_.MaxStreamsPerConnection();
   if (is_server()) {
@@ -479,23 +474,6 @@ void QuicSession::OnConfigNegotiated() {
   }
   set_max_open_streams(max_streams);
 
-  if (version == QUIC_VERSION_19) {
-    // QUIC_VERSION_19 doesn't support independent stream/session flow
-    // control windows.
-    if (config_.HasReceivedInitialFlowControlWindowBytes()) {
-      // Streams which were created before the SHLO was received (0-RTT
-      // requests) are now informed of the peer's initial flow control window.
-      QuicStreamOffset new_window =
-          config_.ReceivedInitialFlowControlWindowBytes();
-      OnNewStreamFlowControlWindow(new_window);
-      OnNewSessionFlowControlWindow(new_window);
-    }
-
-    return;
-  }
-
-  // QUIC_VERSION_21 and higher can have independent stream and session flow
-  // control windows.
   if (config_.HasReceivedInitialStreamFlowControlWindowBytes()) {
     // Streams which were created before the SHLO was received (0-RTT
     // requests) are now informed of the peer's initial flow control window.
@@ -748,7 +726,6 @@ bool QuicSession::GetSSLInfo(SSLInfo* ssl_info) const {
 
 void QuicSession::PostProcessAfterData() {
   STLDeleteElements(&closed_streams_);
-  closed_streams_.clear();
 
   if (connection()->connected() &&
       locally_closed_streams_highest_offset_.size() > max_open_streams_) {
@@ -757,15 +734,6 @@ void QuicSession::PostProcessAfterData() {
   }
 }
 
-void QuicSession::OnSuccessfulVersionNegotiation(const QuicVersion& version) {
-  // Disable stream level flow control based on negotiated version. Streams may
-  // have been created with a different version.
-  if (version < QUIC_VERSION_21) {
-    GetCryptoStream()->flow_controller()->Disable();
-    headers_stream_->flow_controller()->Disable();
-  }
-}
-
 bool QuicSession::IsConnectionFlowControlBlocked() const {
   return flow_controller_->IsBlocked();
 }