arc: Fix missing notification on extended desktop

ui/arc/notification/arc_custom_notification_view.cc

 // Copyright 2016 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 "ui/arc/notification/arc_custom_notification_view.h"
 
 #include "base/auto_reset.h"
 #include "components/exo/notification_surface.h"
 #include "components/exo/surface.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ skipping 292 matching lines @@
   slide_helper_->Update();
 }
 
 void ArcCustomNotificationView::ViewHierarchyChanged(
     const views::View::ViewHierarchyChangedDetails& details) {
   views::Widget* widget = GetWidget();
 
   if (!details.is_add) {
     // Resets slide helper when this view is removed from its parent.
     slide_helper_.reset();
-  }
 
-  // Bail if native_view() has attached to a different widget.
-  if (widget && native_view() &&
-      views::Widget::GetTopLevelWidgetForNativeView(native_view()) != widget) {
-    return;
+    // Bail if this view is no longer attached to a widget or native_view() has
+    // attached to a different widget.
+    if (!widget || (native_view() &&
+                    views::Widget::GetTopLevelWidgetForNativeView(
+                        native_view()) != widget)) {
+      return;
+    }
   }
 
   views::NativeViewHost::ViewHierarchyChanged(details);
 
   if (!widget || !surface_ || !details.is_add)
     return;
 
   AttachSurface();
 }
 
@@ skipping 114 matching lines @@
 
 void ArcCustomNotificationView::OnNotificationSurfaceRemoved(
     exo::NotificationSurface* surface) {
   if (surface->notification_id() != notification_key_)
     return;
 
   SetSurface(nullptr);
 }
 
 }  // namespace arc