Moves maintaining ShellObservers back to Shell

ash/common/system/chromeos/cast/tray_cast.cc

 // Copyright 2015 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/chromeos/cast/tray_cast.h"
 
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 11 matching lines @@
 #include "ash/common/system/tray/tray_constants.h"
 #include "ash/common/system/tray/tray_details_view.h"
 #include "ash/common/system/tray/tray_item_more.h"
 #include "ash/common/system/tray/tray_item_view.h"
 #include "ash/common/system/tray/tray_utils.h"
 #include "ash/common/wm_shell.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "ash/public/interfaces/cast_config.mojom.h"
 #include "ash/resources/grit/ash_resources.h"
 #include "ash/resources/vector_icons/vector_icons.h"
+#include "ash/shell.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "base/bind.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/paint_vector_icon.h"
 #include "ui/gfx/text_elider.h"
 #include "ui/views/background.h"
 #include "ui/views/border.h"
@@ skipping 407 matching lines @@
     WmShell::Get()->cast_config()->CastToSink(it->second.Clone());
     WmShell::Get()->RecordUserMetricsAction(
         UMA_STATUS_AREA_DETAILED_CAST_VIEW_LAUNCH_CAST);
   }
 }
 
 }  // namespace tray
 
 TrayCast::TrayCast(SystemTray* system_tray)
     : SystemTrayItem(system_tray, UMA_CAST) {
-  WmShell::Get()->AddShellObserver(this);
+  Shell::GetInstance()->AddShellObserver(this);
   WmShell::Get()->cast_config()->AddObserver(this);
   WmShell::Get()->cast_config()->RequestDeviceRefresh();
 }
 
 TrayCast::~TrayCast() {
   WmShell::Get()->cast_config()->RemoveObserver(this);
-  WmShell::Get()->RemoveShellObserver(this);
+  Shell::GetInstance()->RemoveShellObserver(this);
 }
 
 void TrayCast::StartCastForTest(const std::string& receiver_id) {
   if (detailed_ != nullptr)
     detailed_->SimulateViewClickedForTest(receiver_id);
 }
 
 void TrayCast::StopCastForTest() {
   default_->cast_view()->StopCasting();
 }
@@ skipping 86 matching lines @@
 
   return false;
 }
 
 void TrayCast::OnCastingSessionStartedOrStopped(bool started) {
   is_mirror_casting_ = started;
   UpdatePrimaryView();
 }
 
 }  // namespace ash