Move yet more 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 16 matching lines @@
 
   icon_->SetImage(CreateVectorIcon(kShelfOverviewIcon, kShelfIconColor));
   SetIconBorderForShelfAlignment();
   tray_container()->AddChildView(icon_);
 
   // Since OverviewButtonTray is located on the rightmost position of a
   // horizontal shelf, no separator is required.
   set_separator_visibility(false);
 
   Shell::GetInstance()->AddShellObserver(this);
-  WmShell::Get()->session_controller()->AddSessionStateObserver(this);
+  Shell::Get()->session_controller()->AddSessionStateObserver(this);
 }
 
 OverviewButtonTray::~OverviewButtonTray() {
   Shell::GetInstance()->RemoveShellObserver(this);
-  WmShell::Get()->session_controller()->RemoveSessionStateObserver(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();
   // Toggling overview mode will fail if there is no window to show.
@@ skipping 49 matching lines @@
   const int horizontal_padding = (kTrayItemSize - image.width()) / 2;
   icon_->SetBorder(views::CreateEmptyBorder(
       gfx::Insets(vertical_padding, horizontal_padding)));
 }
 
 void OverviewButtonTray::UpdateIconVisibility() {
   // The visibility of the OverviewButtonTray has diverged from
   // WindowSelectorController::CanSelect. The visibility of the button should
   // not change during transient times in which CanSelect is false. Such as when
   // a modal dialog is present.
-  SessionController* session_controller = WmShell::Get()->session_controller();
+  SessionController* session_controller = Shell::Get()->session_controller();
 
   Shell* shell = Shell::Get();
   SetVisible(
       shell->maximize_mode_controller()->IsMaximizeModeWindowManagerEnabled() &&
       session_controller->IsActiveUserSessionStarted() &&
       !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