Removes WmRootWindowController subclasses

ash/mus/bridge/wm_lookup_mus.cc

 // 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.
 
 #include "ash/mus/bridge/wm_lookup_mus.h"
 
-#include "ash/mus/bridge/wm_root_window_controller_mus.h"
 #include "ash/mus/bridge/wm_shell_mus.h"
 #include "ash/mus/bridge/wm_window_mus.h"
+#include "ash/mus/root_window_controller.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace mus {
 
 WmLookupMus::WmLookupMus() {
   WmLookup::Set(this);
 }
 
 WmLookupMus::~WmLookupMus() {
   if (WmLookupMus::Get() == this)
     WmLookup::Set(nullptr);
 }
 
 WmRootWindowController* WmLookupMus::GetRootWindowControllerWithDisplayId(
     int64_t id) {
-  return WmShellMus::Get()->GetRootWindowControllerWithDisplayId(id);
+  return WmShellMus::Get()
+      ->GetRootWindowControllerWithDisplayId(id)
+      ->ash_root_window_controller()
+      ->wm_root_window_controller();
 }
 
 WmWindow* WmLookupMus::GetWindowForWidget(views::Widget* widget) {
   return WmWindowMus::Get(widget);
 }
 
 }  // namespace mus
 }  // namespace ash