Fix a race in ThreadLocalStorage::StaticSlot::initialized which triggers a TSAN error.

build/sanitizers/tsan_suppressions.cc

 // Copyright 2014 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.
 
 // This file contains the default suppressions for ThreadSanitizer.
 // You can also pass additional suppressions via TSAN_OPTIONS:
 // TSAN_OPTIONS=suppressions=/path/to/suppressions. Please refer to
 // http://dev.chromium.org/developers/testing/threadsanitizer-tsan-v2
 // for more info.
 
@@ skipping 107 matching lines @@
 // http://crbug.com/268924
 "race:base::g_power_monitor\n"
 "race:base::PowerMonitor::PowerMonitor\n"
 "race:base::PowerMonitor::AddObserver\n"
 "race:base::PowerMonitor::RemoveObserver\n"
 "race:base::PowerMonitor::IsOnBatteryPower\n"
 
 // http://crbug.com/258935
 "race:base::Thread::StopSoon\n"
 
-// http://crbug.com/268941
-"race:tracked_objects::ThreadData::tls_index_\n"
-
 // http://crbug.com/272095
 "race:base::g_top_manager\n"
 
 // http://crbug.com/273047
 "race:base::*::g_lazy_tls_ptr\n"
 "race:IPC::SyncChannel::ReceivedSyncMsgQueue::lazy_tls_ptr_\n"
 
 // http://crbug.com/280466
 "race:content::WebRtcAudioCapturer::SetCapturerSource\n"
 
@@ skipping 168 matching lines @@
 // https://crbug.com/459429
 "race:randomnessPid\n"
 
 // https://crbug.com/454655
 "race:content::BrowserTestBase::PostTaskToInProcessRendererAndWait\n"
 
 // End of suppressions.
 ;  // Please keep this semicolon.
 
 #endif  // THREAD_SANITIZER