Moves maintaining root_window_for_new_windows_ to Shell

ash/common/wm/mru_window_tracker.cc

 // Copyright 2013 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/common/wm/mru_window_tracker.h"
 
 #include <algorithm>
 
 #include "ash/common/wm/focus_rules.h"
 #include "ash/common/wm/switchable_windows.h"
@@ skipping 27 matching lines @@
 }
 
 // Returns a list of windows ordered by their stacking order.
 // If |mru_windows| is passed, these windows are moved to the front of the list.
 // It uses the given |should_include_window_predicate| to determine whether to
 // include a window in the returned list or not.
 MruWindowTracker::WindowList BuildWindowListInternal(
     const std::list<WmWindow*>* mru_windows,
     const CanActivateWindowPredicate& should_include_window_predicate) {
   MruWindowTracker::WindowList windows;
-  WmWindow* active_root = WmShell::Get()->GetRootWindowForNewWindows();
+  WmWindow* active_root = Shell::GetWmRootWindowForNewWindows();
   for (WmWindow* window : WmShell::Get()->GetAllRootWindows()) {
     if (window == active_root)
       continue;
     for (size_t i = 0; i < wm::kSwitchableWindowContainerIdsLength; ++i)
       AddTrackedWindows(window, wm::kSwitchableWindowContainerIds[i], &windows);
   }
 
   // Add windows in the active root windows last so that the topmost window
   // in the active root window becomes the front of the list.
   for (size_t i = 0; i < wm::kSwitchableWindowContainerIdsLength; ++i)
@@ skipping 96 matching lines @@
 
 void MruWindowTracker::OnWindowDestroyed(aura::Window* window) {
   // It's possible for OnWindowActivated() to be called after
   // OnWindowDestroying(). This means we need to override OnWindowDestroyed()
   // else we may end up with a deleted window in |mru_windows_|.
   mru_windows_.remove(WmWindow::Get(window));
   window->RemoveObserver(this);
 }
 
 }  // namespace ash