Moves couple of WmShell methods to standalone functions

ash/common/wm/system_modal_container_layout_manager.cc

 // Copyright (c) 2012 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/system_modal_container_layout_manager.h"
 
 #include <cmath>
 
 #include "ash/common/session/session_controller.h"
 #include "ash/common/wm/window_dimmer.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/shell.h"
+#include "ash/wm/window_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
 #include "ui/keyboard/keyboard_controller.h"
 
 namespace ash {
 namespace {
 
 // The center point of the window can diverge this much from the center point
@@ skipping 166 matching lines @@
           window->GetParent()->GetLayoutManager());
   return layout_manager->window_dimmer_ &&
          WmWindow::Get(layout_manager->window_dimmer_->window()) == window;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // SystemModalContainerLayoutManager, private:
 
 void SystemModalContainerLayoutManager::AddModalWindow(WmWindow* window) {
   if (modal_windows_.empty()) {
-    WmWindow* capture_window = WmShell::Get()->GetCaptureWindow();
+    WmWindow* capture_window = WmWindow::Get(wm::GetCaptureWindow());
     if (capture_window)
       capture_window->ReleaseCapture();
   }
   DCHECK(window->IsVisible());
   DCHECK(!base::ContainsValue(modal_windows_, window));
 
   modal_windows_.push_back(window);
   WmShell::Get()->CreateModalBackground(window);
   window->GetParent()->StackChildAtTop(window);
 
@@ skipping 60 matching lines @@
 bool SystemModalContainerLayoutManager::IsBoundsCentered(
     const gfx::Rect& bounds) const {
   gfx::Point window_center = bounds.CenterPoint();
   gfx::Point container_center = GetUsableDialogArea().CenterPoint();
   return std::abs(window_center.x() - container_center.x()) <
              kCenterPixelDelta &&
          std::abs(window_center.y() - container_center.y()) < kCenterPixelDelta;
 }
 
 }  // namespace ash