mash: Migrate SessionStateDelegate access to WmShell.

ash/desktop_background/desktop_background_view.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/desktop_background/desktop_background_view.h"
 
 #include <limits>
 
 #include "ash/ash_export.h"
 #include "ash/common/session/session_state_delegate.h"
@@ skipping 215 matching lines @@
   RootWindowController* root_window_controller =
       GetRootWindowController(root_window);
 
   // Enable wallpaper transition for the following cases:
   // 1. Initial(OOBE) wallpaper animation.
   // 2. Wallpaper fades in from a non empty background.
   // 3. From an empty background, chrome transit to a logged in user session.
   // 4. From an empty background, guest user logged in.
   if (wallpaper_delegate->ShouldShowInitialAnimation() ||
       root_window_controller->animating_wallpaper_controller() ||
-      Shell::GetInstance()->session_state_delegate()->NumberOfLoggedInUsers()) {
+      WmShell::Get()->GetSessionStateDelegate()->NumberOfLoggedInUsers()) {
     ::wm::SetWindowVisibilityAnimationTransition(
         desktop_widget->GetNativeView(), ::wm::ANIMATE_SHOW);
     int duration_override = wallpaper_delegate->GetAnimationDurationOverride();
     if (duration_override) {
       ::wm::SetWindowVisibilityAnimationDuration(
           desktop_widget->GetNativeView(),
           base::TimeDelta::FromMilliseconds(duration_override));
     }
   } else {
     // Disable animation if transition to login screen from an empty background.
     ::wm::SetWindowVisibilityAnimationTransition(
         desktop_widget->GetNativeView(), ::wm::ANIMATE_NONE);
   }
 
   desktop_widget->SetBounds(params.parent->bounds());
   return desktop_widget;
 }
 
 }  // namespace ash