Removes ash::mus::RootWindowController

ash/mus/bridge/wm_lookup_mus.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 ASH_MUS_BRIDGE_WM_LOOKUP_MUS_H_
 #define ASH_MUS_BRIDGE_WM_LOOKUP_MUS_H_
 
 #include <stdint.h>
 
 #include "ash/common/wm_lookup.h"
 #include "base/macros.h"
 
 namespace ash {
 namespace mus {
 
 // WmLookup implementation for mus.
 class WmLookupMus : public WmLookup {
  public:
   WmLookupMus();
   ~WmLookupMus() override;
 
   // WmLookup:
-  ash::RootWindowController* GetRootWindowControllerWithDisplayId(
+  RootWindowController* GetRootWindowControllerWithDisplayId(
       int64_t id) override;
   WmWindow* GetWindowForWidget(views::Widget* widget) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WmLookupMus);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_BRIDGE_WM_LOOKUP_MUS_H_