Moves couple of WmShell methods to standalone functions

ash/common/wm/immersive_context_ash.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/common/wm/immersive_context_ash.h"
 
 #include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/shared/immersive_fullscreen_controller.h"
+#include "ash/wm/window_util.h"
 #include "base/logging.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 
 ImmersiveContextAsh::ImmersiveContextAsh() {}
 
 ImmersiveContextAsh::~ImmersiveContextAsh() {}
@@ skipping 27 matching lines @@
     views::PointerWatcher* watcher,
     views::PointerWatcherEventTypes events) {
   WmShell::Get()->AddPointerWatcher(watcher, events);
 }
 
 void ImmersiveContextAsh::RemovePointerWatcher(views::PointerWatcher* watcher) {
   WmShell::Get()->RemovePointerWatcher(watcher);
 }
 
 bool ImmersiveContextAsh::DoesAnyWindowHaveCapture() {
-  return WmShell::Get()->GetCaptureWindow() != nullptr;
+  return wm::GetCaptureWindow() != nullptr;
 }
 
 bool ImmersiveContextAsh::IsMouseEventsEnabled() {
   return WmShell::Get()->IsMouseEventsEnabled();
 }
 
 }  // namespace ash