Automated IWYU fix for TaskRunner includes.

components/leveldb/leveldb_service_impl.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 COMPONENTS_LEVELDB_LEVELDB_SERVICE_IMPL_H_
 #define COMPONENTS_LEVELDB_LEVELDB_SERVICE_IMPL_H_
 
 #include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
 #include "components/leveldb/leveldb_mojo_proxy.h"
 #include "components/leveldb/public/interfaces/leveldb.mojom.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 
 namespace leveldb {
 
 // Creates LevelDBDatabases based scoped to a |directory|/|dbname|.
 class LevelDBServiceImpl : public mojom::LevelDBService {
  public:
   // The |file_task_runner| is used to run tasks to interact with the
@@ skipping 25 matching lines @@
   // threads that want to call file stuff, we create a dedicated thread to send
   // and receive mojo message calls.
   scoped_refptr<LevelDBMojoProxy> thread_;
 
   DISALLOW_COPY_AND_ASSIGN(LevelDBServiceImpl);
 };
 
 }  // namespace leveldb
 
 #endif  // COMPONENTS_LEVELDB_LEVELDB_SERVICE_IMPL_H_