mash: Convert TrayBackgroundView to wm common types

ash/system/chromeos/virtual_keyboard/virtual_keyboard_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/system/chromeos/virtual_keyboard/virtual_keyboard_tray.h"
 
 #include "ash/common/keyboard/keyboard_ui.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf_util.h"
@@ skipping 10 matching lines @@
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/events/event.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/paint_vector_icon.h"
 #include "ui/gfx/vector_icons_public.h"
 #include "ui/views/controls/button/image_button.h"
 
 namespace ash {
 
 VirtualKeyboardTray::VirtualKeyboardTray(StatusAreaWidget* status_area_widget)
-    : TrayBackgroundView(status_area_widget),
-      button_(NULL) {
+    : TrayBackgroundView(status_area_widget->wm_shelf()), button_(nullptr) {
   button_ = new views::ImageButton(this);
   if (MaterialDesignController::IsShelfMaterial()) {
     gfx::ImageSkia image_md =
         CreateVectorIcon(gfx::VectorIconId::SHELF_KEYBOARD, kShelfIconColor);
     button_->SetImage(views::CustomButton::STATE_NORMAL, &image_md);
   } else {
     gfx::ImageSkia* image_non_md =
         ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(
             IDR_AURA_UBER_TRAY_VIRTUAL_KEYBOARD);
     button_->SetImage(views::CustomButton::STATE_NORMAL, image_non_md);
@@ skipping 62 matching lines @@
                                         const ui::Event& event) {
   DCHECK_EQ(button_, sender);
   PerformAction(event);
 }
 
 void VirtualKeyboardTray::OnKeyboardEnabledStateChanged(bool new_value) {
   SetVisible(Shell::GetInstance()->keyboard_ui()->IsEnabled());
 }
 
 }  // namespace ash