aura-mus: Make StackAtTop() proxy to the window manager.

services/ui/ws/window_tree.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/window_tree.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 1607 matching lines @@
   }
 
   DCHECK(!parent->children().empty());
   if (parent->children().back() == window) {
     // Ignore this call; the client didn't know they were already at the top.
     DVLOG(3) << "StackAtTop ignored (already at top)";
     client()->OnChangeCompleted(change_id, true);
     return;
   }
 
-  ServerWindow* relative_window = parent->children().back();
-  Operation op(this, window_server_, OperationType::REORDER_WINDOW);
-  window->Reorder(relative_window, mojom::OrderDirection::ABOVE);
-  window_server_->ProcessWindowReorder(window, relative_window,
-                                       mojom::OrderDirection::ABOVE);
+  WindowManagerDisplayRoot* display_root = GetWindowManagerDisplayRoot(window);
+  if (!display_root) {
+    DVLOG(1) << "StackAtTop (no display root)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
 
-  client()->OnChangeCompleted(change_id, true);
+  // Window reordering assumes that it is the owner of parent who is sending
+  // the message, and does not deal gracefully with other clients reordering
+  // their windows. So tell the window manager to send us a reorder message.
+  WindowTree* wm_tree = display_root->window_manager_state()->window_tree();
+  const uint32_t wm_change_id =
+      window_server_->GenerateWindowManagerChangeId(this, change_id);
+  wm_tree->window_manager_internal_->WmStackAtTop(
+      wm_change_id, wm_tree->ClientWindowIdForWindow(window).id);
 }
 
 void WindowTree::GetWindowManagerClient(
     mojo::AssociatedInterfaceRequest<mojom::WindowManagerClient> internal) {
   if (!access_policy_->CanSetWindowManager() || !window_manager_internal_ ||
       window_manager_internal_client_binding_) {
     return;
   }
   window_manager_internal_client_binding_.reset(
       new mojo::AssociatedBinding<mojom::WindowManagerClient>(
@@ skipping 427 matching lines @@
   client()->OnCompleteDrop(client_window_id.id, event_flags, cursor_offset,
                            effect_bitmask, callback);
 }
 
 void WindowTree::PerformOnDragDropDone() {
   client()->OnDragDropDone();
 }
 
 }  // namespace ws
 }  // namespace ui