Automated IWYU fix for TaskRunner includes.

ui/aura/mus/window_tree_client.h

 // 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.
 
 #ifndef UI_AURA_MUS_WINDOW_TREE_CLIENT_H_
 #define UI_AURA_MUS_WINDOW_TREE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/atomicops.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "base/single_thread_task_runner.h"
 #include "cc/surfaces/local_surface_id_allocator.h"
 #include "mojo/public/cpp/bindings/associated_binding.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 #include "services/ui/public/interfaces/window_tree.mojom.h"
 #include "ui/aura/aura_export.h"
 #include "ui/aura/client/transient_window_client_observer.h"
 #include "ui/aura/mus/capture_synchronizer_delegate.h"
 #include "ui/aura/mus/drag_drop_controller_host.h"
 #include "ui/aura/mus/focus_synchronizer_delegate.h"
 #include "ui/aura/mus/mus_types.h"
@@ skipping 611 matching lines @@
   gfx::Insets normal_client_area_insets_;
 
   base::WeakPtrFactory<WindowTreeClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClient);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_WINDOW_TREE_CLIENT_H_