Update from https://crrev.com/307330

net/quic/quic_sent_packet_manager_test.cc

 // Copyright 2013 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/quic_sent_packet_manager.h"
 
 #include "base/stl_util.h"
 #include "net/quic/quic_flags.h"
 #include "net/quic/test_tools/quic_config_peer.h"
 #include "net/quic/test_tools/quic_sent_packet_manager_peer.h"
@@ skipping 1366 matching lines @@
   QuicTagVector options;
   options.push_back(kPACE);
   QuicConfigPeer::SetReceivedConnectionOptions(&config, options);
   EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _, /* using_pacing= */ true));
   manager_.SetFromConfig(config);
 
   EXPECT_TRUE(manager_.using_pacing());
 }
 
+TEST_F(QuicSentPacketManagerTest, EnablePacingViaFlag) {
+  EXPECT_FALSE(manager_.using_pacing());
+
+  // If pacing is enabled via command-line flag, it will be turned on,
+  // regardless of the contents of the config.
+  ValueRestore<bool> old_flag(&FLAGS_quic_enable_pacing, true);
+  QuicConfig config;
+  EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _, /* using_pacing= */ true));
+  manager_.SetFromConfig(config);
+
+  EXPECT_TRUE(manager_.using_pacing());
+}
+
 TEST_F(QuicSentPacketManagerTest, NegotiateReceiveWindowFromOptions) {
   EXPECT_EQ(kDefaultSocketReceiveBuffer,
             QuicSentPacketManagerPeer::GetReceiveWindow(&manager_));
 
   // Try to set a size below the minimum and ensure it gets set to the min.
   QuicConfig client_config;
   QuicConfigPeer::SetReceivedSocketReceiveBuffer(&client_config, 1024);
   EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _, _));
   EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
   manager_.SetFromConfig(client_config);
@@ skipping 50 matching lines @@
   EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
   manager_.SetFromConfig(config);
 
   EXPECT_EQ(0, manager_.GetRttStats()->smoothed_rtt().ToMicroseconds());
   EXPECT_EQ(initial_rtt_us, manager_.GetRttStats()->initial_rtt_us());
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net