Moves maintaining ShellObservers back to Shell

ash/common/system/chromeos/session/logout_confirmation_controller.cc

 // Copyright 2014 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/system/chromeos/session/logout_confirmation_controller.h"
 
 #include <utility>
 
 #include "ash/common/login_status.h"
 #include "ash/common/system/chromeos/session/logout_confirmation_dialog.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/system/tray/system_tray_notifier.h"
 #include "ash/common/wm_shell.h"
+#include "ash/shell.h"
 #include "base/location.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/tick_clock.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace {
 const int kLogoutConfirmationDelayInSeconds = 20;
 }
 
 LogoutConfirmationController::LogoutConfirmationController(
     const base::Closure& logout_closure)
     : clock_(new base::DefaultTickClock),
       logout_closure_(logout_closure),
       dialog_(NULL),
       logout_timer_(false, false) {
   if (WmShell::HasInstance()) {
-    WmShell::Get()->AddShellObserver(this);
+    Shell::GetInstance()->AddShellObserver(this);
     WmShell::Get()->system_tray_notifier()->AddLastWindowClosedObserver(this);
   }
 }
 
 LogoutConfirmationController::~LogoutConfirmationController() {
   if (WmShell::HasInstance()) {
-    WmShell::Get()->RemoveShellObserver(this);
+    Shell::GetInstance()->RemoveShellObserver(this);
     WmShell::Get()->system_tray_notifier()->RemoveLastWindowClosedObserver(
         this);
   }
   if (dialog_)
     dialog_->ControllerGone();
 }
 
 void LogoutConfirmationController::ConfirmLogout(base::TimeTicks logout_time) {
   if (!logout_time_.is_null() && logout_time >= logout_time_) {
     // If a confirmation dialog is already being shown and its countdown expires
@@ skipping 50 matching lines @@
   }
 
   // Ask the user to confirm logout if a public session is in progress and the
   // screen is not locked.
   ConfirmLogout(
       base::TimeTicks::Now() +
       base::TimeDelta::FromSeconds(kLogoutConfirmationDelayInSeconds));
 }
 
 }  // namespace ash