Nix GetRootWindowController, use RootWindowController::ForWindow.

ash/display/cursor_window_controller.cc

 // 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.
 
 #include "ash/display/cursor_window_controller.h"
 
 #include "ash/ash_constants.h"
 #include "ash/display/mirror_window_controller.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/public/cpp/shell_window_ids.h"
@@ skipping 144 matching lines @@
     return;
   }
 
   display_ = display;
   aura::Window* root_window =
       Shell::Get()->window_tree_host_manager()->GetRootWindowForDisplayId(
           display.id());
   if (!root_window)
     return;
 
-  SetContainer(GetRootWindowController(root_window)
+  SetContainer(RootWindowController::ForWindow(root_window)
                    ->GetContainer(kShellWindowId_MouseCursorContainer));
   SetBoundsInScreen(display.bounds());
   // Updates the hot point based on the current display.
   UpdateCursorImage();
 }
 
 void CursorWindowController::UpdateLocation() {
   if (!cursor_window_)
     return;
   gfx::Point point = aura::Env::GetInstance()->last_mouse_location();
@@ skipping 148 matching lines @@
     cursor_window_->Show();
   else
     cursor_window_->Hide();
 }
 
 const gfx::ImageSkia& CursorWindowController::GetCursorImageForTest() const {
   return delegate_->cursor_image();
 }
 
 }  // namespace ash