ScopedTrackers to help pin down where IOThread::InitSystemRequestContextOnIOThread is janky

net/quic/quic_stream_factory.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/quic_stream_factory.h"
 
 #include <set>
 
 #include "base/cpu.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 604 matching lines @@
       load_server_info_timeout_ms_(load_server_info_timeout),
       load_server_info_timeout_srtt_multiplier_(
           load_server_info_timeout_srtt_multiplier),
       enable_truncated_connection_ids_(enable_truncated_connection_ids),
       enable_connection_racing_(false),
       port_seed_(random_generator_->RandUint64()),
       check_persisted_supports_quic_(true),
       task_runner_(nullptr),
       weak_factory_(this) {
   DCHECK(transport_security_state_);
+  // TODO(michaeln): Remove ScopedTracker below once crbug.com/454983 is fixed
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "454983 QuicStreamFactory::QuicStreamFactory"));
   crypto_config_.set_user_agent_id(user_agent_id);
   crypto_config_.AddCanonicalSuffix(".c.youtube.com");
   crypto_config_.AddCanonicalSuffix(".googlevideo.com");
   crypto_config_.SetProofVerifier(
       new ProofVerifierChromium(cert_verifier, transport_security_state));
   crypto_config_.SetChannelIDSource(
       new ChannelIDSourceChromium(channel_id_service));
   base::CPU cpu;
   if (cpu.has_aesni() && cpu.has_avx())
     crypto_config_.PreferAesGcm();
@@ skipping 699 matching lines @@
   http_server_properties_->ClearAlternateProtocol(server);
   http_server_properties_->SetAlternateProtocol(
       server, alternate.port, alternate.protocol, 1);
   DCHECK_EQ(QUIC,
             http_server_properties_->GetAlternateProtocol(server).protocol);
   DCHECK(http_server_properties_->WasAlternateProtocolRecentlyBroken(
       server));
 }
 
 }  // namespace net