Moves maintaining ShellObservers back to Shell

ash/common/system/web_notification/ash_popup_alignment_delegate.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/web_notification/ash_popup_alignment_delegate.h"
 
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
-#include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/root_window_controller.h"
+#include "ash/shell.h"
 #include "base/i18n/rtl.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/message_center/message_center_style.h"
 #include "ui/message_center/views/message_popup_collection.h"
 #include "ui/wm/core/shadow_types.h"
 
 namespace ash {
 
 namespace {
 
 const int kToastMarginX = 7;
 
 // If there should be no margin for the first item, this value needs to be
 // substracted to flush the message to the shelf (the width of the border +
 // shadow).
 const int kNoToastMarginBorderAndShadowOffset = 2;
 
 }  // namespace
 
 AshPopupAlignmentDelegate::AshPopupAlignmentDelegate(WmShelf* shelf)
     : screen_(NULL), shelf_(shelf), tray_bubble_height_(0) {
   shelf_->AddObserver(this);
 }
 
 AshPopupAlignmentDelegate::~AshPopupAlignmentDelegate() {
   if (screen_)
     screen_->RemoveObserver(this);
-  WmShell::Get()->RemoveShellObserver(this);
+  Shell::GetInstance()->RemoveShellObserver(this);
   shelf_->RemoveObserver(this);
 }
 
 void AshPopupAlignmentDelegate::StartObserving(
     display::Screen* screen,
     const display::Display& display) {
   screen_ = screen;
   work_area_ = display.work_area();
   screen->AddObserver(this);
-  WmShell::Get()->AddShellObserver(this);
+  Shell::GetInstance()->AddShellObserver(this);
   if (tray_bubble_height_ > 0)
     UpdateWorkArea();
 }
 
 void AshPopupAlignmentDelegate::SetTrayBubbleHeight(int height) {
   tray_bubble_height_ = height;
 
   // If the shelf is shown during auto-hide state, the distance from the edge
   // should be reduced by the height of shelf's shown height.
   if (shelf_->GetVisibilityState() == SHELF_AUTO_HIDE &&
@@ skipping 95 matching lines @@
     const display::Display& old_display) {}
 
 void AshPopupAlignmentDelegate::OnDisplayMetricsChanged(
     const display::Display& display,
     uint32_t metrics) {
   if (GetCurrentDisplay().id() == display.id())
     UpdateWorkArea();
 }
 
 }  // namespace ash