Removes a couple more functions from WmWindow

ash/mus/window_manager.cc

 // Copyright 2015 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/window_manager.h"
 
 #include <stdint.h>
 
 #include <utility>
 
@@ skipping 227 matching lines @@
     const display::Display& display,
     RootWindowController::RootWindowType root_window_type) {
   RootWindowSettings* root_window_settings =
       InitRootWindowSettings(window_tree_host->window());
   root_window_settings->display_id = display.id();
   std::unique_ptr<RootWindowController> root_window_controller(
       new RootWindowController(nullptr, window_tree_host.release()));
   root_window_controller->Init(root_window_type);
   // TODO: To avoid lots of IPC AddActivationParent() should take an array.
   // http://crbug.com/682048.
-  WmWindow* root_window = root_window_controller->GetWindow();
+  aura::Window* root_window = root_window_controller->GetRootWindow();
   for (size_t i = 0; i < kNumActivatableShellWindowIds; ++i) {
     window_manager_client_->AddActivationParent(
-        root_window->GetChildByShellWindowId(kActivatableShellWindowIds[i])
-            ->aura_window());
+        root_window->GetChildById(kActivatableShellWindowIds[i]));
   }
   root_window_controllers_.insert(std::move(root_window_controller));
 }
 
 void WindowManager::DestroyRootWindowController(
     RootWindowController* root_window_controller,
     bool in_shutdown) {
   if (!in_shutdown && root_window_controllers_.size() > 1) {
     DCHECK_NE(root_window_controller, GetPrimaryRootWindowController());
     root_window_controller->MoveWindowsTo(
@@ skipping 299 matching lines @@
 bool WindowManager::IsWindowActive(aura::Window* window) {
   return Shell::Get()->activation_client()->GetActiveWindow() == window;
 }
 
 void WindowManager::OnWmDeactivateWindow(aura::Window* window) {
   Shell::Get()->activation_client()->DeactivateWindow(window);
 }
 
 }  // namespace mus
 }  // namespace ash