Remove task.h and finish base::Bind() migration.

ui/aura/root_window.h

 // 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.
 
 #ifndef UI_AURA_ROOT_WINDOW_H_
 #define UI_AURA_ROOT_WINDOW_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
-#include "base/task.h"
 #include "ui/aura/aura_export.h"
 #include "ui/aura/cursor.h"
 #include "ui/aura/focus_manager.h"
 #include "ui/aura/window.h"
 #include "ui/base/events.h"
 #include "ui/gfx/compositor/compositor.h"
 #include "ui/gfx/compositor/layer_animation_observer.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/point.h"
 
@@ skipping 195 matching lines @@
   Window* mouse_moved_handler_;
   Window* focused_window_;
   Window* touch_event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindow);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_H_