Automated IWYU fix for TaskRunner includes.

remoting/host/linux/certificate_watcher.h

 // Copyright 2016 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.
 
 #ifndef REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_
 #define REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_
 
 #include <memory>
 
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
 #include "base/timer/timer.h"
 #include "remoting/host/host_status_monitor.h"
 #include "remoting/host/host_status_observer.h"
 
 namespace remoting {
 
 class CertDbContentWatcher;
 
 // This class watches the cert database and notifies the host to restart when
 // a change of the database is detected. The runner script will restart the host
@@ skipping 70 matching lines @@
   base::TimeDelta delay_;
 
   base::WeakPtrFactory<CertificateWatcher> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CertificateWatcher);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_LINUX_CERTIFICATE_WATCHER_H_