Moves maintaining ShellObservers back to Shell

ash/common/system/web_notification/ash_popup_alignment_delegate.cc

Index: ash/common/system/web_notification/ash_popup_alignment_delegate.cc
diff --git a/ash/common/system/web_notification/ash_popup_alignment_delegate.cc b/ash/common/system/web_notification/ash_popup_alignment_delegate.cc
index 46b2719773ec0cb092f1783a7800163dff3a1c34..b32732b4a19ea0da9a7bbb545fd74ef88cebfd22 100644
--- a/ash/common/system/web_notification/ash_popup_alignment_delegate.cc
+++ b/ash/common/system/web_notification/ash_popup_alignment_delegate.cc
@@ -6,11 +6,11 @@
 
 #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"
@@ -40,7 +40,7 @@ AshPopupAlignmentDelegate::AshPopupAlignmentDelegate(WmShelf* shelf)
 AshPopupAlignmentDelegate::~AshPopupAlignmentDelegate() {
   if (screen_)
     screen_->RemoveObserver(this);
-  WmShell::Get()->RemoveShellObserver(this);
+  Shell::GetInstance()->RemoveShellObserver(this);
   shelf_->RemoveObserver(this);
 }
 
@@ -50,7 +50,7 @@ void AshPopupAlignmentDelegate::StartObserving(
   screen_ = screen;
   work_area_ = display.work_area();
   screen->AddObserver(this);
-  WmShell::Get()->AddShellObserver(this);
+  Shell::GetInstance()->AddShellObserver(this);
   if (tray_bubble_height_ > 0)
     UpdateWorkArea();
 }