mash: Convert WebNotificationTray to wm common types

ash/system/web_notification/ash_popup_alignment_delegate.cc

Index: ash/system/web_notification/ash_popup_alignment_delegate.cc
diff --git a/ash/system/web_notification/ash_popup_alignment_delegate.cc b/ash/system/web_notification/ash_popup_alignment_delegate.cc
index 82444a989703cb9d447556215256ba86a230c41a..f673c21166409bb9433ddcc6c4334dce390153f7 100644
--- a/ash/system/web_notification/ash_popup_alignment_delegate.cc
+++ b/ash/system/web_notification/ash_popup_alignment_delegate.cc
@@ -7,6 +7,8 @@
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/shelf_types.h"
 #include "ash/common/shelf/wm_shelf.h"
+#include "ash/common/shell_window_ids.h"
+#include "ash/common/wm_root_window_controller.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "base/i18n/rtl.h"
@@ -104,6 +106,16 @@ void AshPopupAlignmentDelegate::RecomputeAlignment(
   // Nothing needs to be done.
 }
 
+void AshPopupAlignmentDelegate::ConfigureWidgetInitParamsForContainer(
+    views::Widget* widget,
+    views::Widget::InitParams* init_params) {
+  // On ash, popups go in the status container.
+  shelf_->GetWindow()
+      ->GetRootWindowController()
+      ->ConfigureWidgetInitParamsForContainer(
+          widget, kShellWindowId_StatusContainer, init_params);
+}
+
 ShelfAlignment AshPopupAlignmentDelegate::GetAlignment() const {
   return shelf_->GetAlignment();
 }