Automated IWYU fix for TaskRunner includes.

chrome/browser/io_thread.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 "chrome/browser/io_thread.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/base64.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/leak_tracker.h"
 #include "base/environment.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/task_scheduler/post_task.h"
 #include "base/threading/thread.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 1060 matching lines @@
 
   // TODO(rtenneti): We should probably use HttpServerPropertiesManager for the
   // system URLRequestContext too. There's no reason this should be tied to a
   // profile.
   return context;
 }
 
 metrics::UpdateUsagePrefCallbackType IOThread::GetMetricsDataUseForwarder() {
   return base::Bind(&UpdateMetricsUsagePrefsOnUIThread);
 }