ash: Move ShelfWidget ownership to WmShelf and refactor access to it

ash/shell/window_type_launcher.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/shell/window_type_launcher.h"
 
 #include <utility>
 
 #include "ash/common/session/session_state_delegate.h"
-#include "ash/common/shelf/shelf_widget.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/system/status_area_widget.h"
 #include "ash/common/system/web_notification/web_notification_tray.h"
 #include "ash/common/wm_shell.h"
 #include "ash/content/shell_content_state.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/shell/example_factory.h"
 #include "ash/shell/panel_window.h"
 #include "ash/shell/toplevel_window.h"
@@ skipping 290 matching lines @@
     notification.reset(new message_center::Notification(
         message_center::NOTIFICATION_TYPE_SIMPLE, "id0",
         base::ASCIIToUTF16("Test Shell Web Notification"),
         base::ASCIIToUTF16("Notification message body."), gfx::Image(),
         base::ASCIIToUTF16("www.testshell.org"), GURL(),
         message_center::NotifierId(message_center::NotifierId::APPLICATION,
                                    "test-id"),
         message_center::RichNotificationData(), NULL /* delegate */));
 
     Shell::GetPrimaryRootWindowController()
-        ->shelf_widget()
-        ->status_area_widget()
+        ->GetStatusAreaWidget()
         ->web_notification_tray()
         ->message_center()
         ->AddNotification(std::move(notification));
   } else if (sender == examples_button_) {
     views::examples::ShowExamplesWindowWithContent(
         views::examples::DO_NOTHING_ON_CLOSE,
         ShellContentState::GetInstance()->GetActiveBrowserContext(), NULL);
   }
 }
 
@@ skipping 26 matching lines @@
                                               views::MenuRunner::ASYNC));
   if (menu_runner_->RunMenuAt(GetWidget(), NULL, gfx::Rect(point, gfx::Size()),
                               views::MENU_ANCHOR_TOPLEFT,
                               source_type) == MenuRunner::MENU_DELETED) {
     return;
   }
 }
 
 }  // namespace shell
 }  // namespace ash