Promotes more accessors from WmShell to Shell

ash/common/system/overview/overview_button_tray.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/overview/overview_button_tray.h"
 
 #include "ash/common/session/session_controller.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/system/tray/tray_constants.h"
@@ skipping 30 matching lines @@
   Shell::GetInstance()->RemoveShellObserver(this);
   Shell::Get()->session_controller()->RemoveSessionStateObserver(this);
 }
 
 void OverviewButtonTray::UpdateAfterLoginStatusChange(LoginStatus status) {
   UpdateIconVisibility();
 }
 
 bool OverviewButtonTray::PerformAction(const ui::Event& event) {
   WindowSelectorController* controller =
-      WmShell::Get()->window_selector_controller();
+      Shell::Get()->window_selector_controller();
   // Toggling overview mode will fail if there is no window to show.
   bool performed = controller->ToggleOverview();
   WmShell::Get()->RecordUserMetricsAction(UMA_TRAY_OVERVIEW);
   return performed;
 }
 
 void OverviewButtonTray::SessionStateChanged(
     session_manager::SessionState state) {
   UpdateIconVisibility();
 }
@@ skipping 56 matching lines @@
       !session_controller->IsScreenLocked() &&
       session_controller->GetSessionState() ==
           session_manager::SessionState::ACTIVE &&
       shell->system_tray_delegate()->GetUserLoginStatus() !=
           LoginStatus::KIOSK_APP &&
       shell->system_tray_delegate()->GetUserLoginStatus() !=
           LoginStatus::ARC_KIOSK_APP);
 }
 
 }  // namespace ash