QUIC enable server push by default. Guarded by FLAGS_quic_enable_server_push_by_default.

net/quic/core/quic_server_session_base.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_server_session_base.h"
 
 #include "base/logging.h"
 #include "net/quic/core/proto/cached_network_parameters.pb.h"
 #include "net/quic/core/quic_bug_tracker.h"
 #include "net/quic/core/quic_connection.h"
@@ skipping 13 matching lines @@
     const QuicCryptoServerConfig* crypto_config,
     QuicCompressedCertsCache* compressed_certs_cache)
     : QuicSpdySession(connection, config),
       crypto_config_(crypto_config),
       compressed_certs_cache_(compressed_certs_cache),
       visitor_(visitor),
       helper_(helper),
       bandwidth_resumption_enabled_(false),
       bandwidth_estimate_sent_to_client_(QuicBandwidth::Zero()),
       last_scup_time_(QuicTime::Zero()),
-      last_scup_packet_number_(0),
-      server_push_enabled_(false) {}
+      last_scup_packet_number_(0) {}
 
 QuicServerSessionBase::~QuicServerSessionBase() {}
 
 void QuicServerSessionBase::Initialize() {
   crypto_stream_.reset(
       CreateQuicCryptoServerStream(crypto_config_, compressed_certs_cache_));
   QuicSpdySession::Initialize();
 }
 
 void QuicServerSessionBase::OnConfigNegotiated() {
   QuicSpdySession::OnConfigNegotiated();
 
   if (!config()->HasReceivedConnectionOptions()) {
     return;
   }
 
   // Enable bandwidth resumption if peer sent correct connection options.
   const bool last_bandwidth_resumption =
       ContainsQuicTag(config()->ReceivedConnectionOptions(), kBWRE);
   const bool max_bandwidth_resumption =
       ContainsQuicTag(config()->ReceivedConnectionOptions(), kBWMX);
   bandwidth_resumption_enabled_ =
       last_bandwidth_resumption || max_bandwidth_resumption;
-  server_push_enabled_ =
-      ContainsQuicTag(config()->ReceivedConnectionOptions(), kSPSH);
+
+  if (!FLAGS_quic_enable_server_push_by_default ||
+      connection()->version() < QUIC_VERSION_35) {
+    set_server_push_enabled(
+        ContainsQuicTag(config()->ReceivedConnectionOptions(), kSPSH));
+  }
 
   // If the client has provided a bandwidth estimate from the same serving
   // region as this server, then decide whether to use the data for bandwidth
   // resumption.
   const CachedNetworkParameters* cached_network_params =
       crypto_stream_->PreviousCachedNetworkParams();
   if (cached_network_params != nullptr &&
       cached_network_params->serving_region() == serving_region_) {
     // Log the received connection parameters, regardless of how they
     // get used for bandwidth resumption.
@@ skipping 166 matching lines @@
 
 int32_t QuicServerSessionBase::BandwidthToCachedParameterBytesPerSecond(
     const QuicBandwidth& bandwidth) {
   int64_t bytes_per_second = bandwidth.ToBytesPerSecond();
   return (bytes_per_second > static_cast<int64_t>(INT32_MAX)
               ? INT32_MAX
               : static_cast<int32_t>(bytes_per_second));
 }
 
 }  // namespace net