Remove FrameSinkId hierarchy when unparenting ServerWindow.

services/ui/ws/server_window.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 "services/ui/ws/server_window.h"
 
 #include <inttypes.h>
 #include <stddef.h>
 
 #include "base/memory/ptr_util.h"
@@ skipping 128 matching lines @@
 }
 
 void ServerWindow::Remove(ServerWindow* child) {
   // We assume validation checks happened else where.
   DCHECK(child);
   DCHECK(child != this);
   DCHECK(child->parent() == this);
 
   for (auto& observer : child->observers_)
     observer.OnWillChangeWindowHierarchy(child, nullptr, this);
+
   RemoveImpl(child);
 
+  if (GetRoot() != nullptr)
+    child->ProcessRootChanged(GetRoot(), nullptr);
+
   // Stack the child properly if it is a transient child of a sibling.
   if (child->transient_parent_ && child->transient_parent_->parent() == this)
     RestackTransientDescendants(child->transient_parent_, &GetStackingTarget,
                                 &ReorderImpl);
 
   for (auto& observer : child->observers_)
     observer.OnWindowHierarchyChanged(child, nullptr, this);
 }
 
 void ServerWindow::Reorder(ServerWindow* relative,
@@ skipping 316 matching lines @@
   window->OnStackingChanged();
 }
 
 // static
 ServerWindow** ServerWindow::GetStackingTarget(ServerWindow* window) {
   return &window->stacking_target_;
 }
 
 }  // namespace ws
 }  // namespace ui