Fixs bug in notifying clients about hierarchy changes

ui/aura/mus/window_tree_client.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 "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 337 matching lines @@
     const InFlightChange& change) {
   InFlightChange* existing_change = GetOldestInFlightChangeMatching(change);
   if (!existing_change)
     return false;
 
   existing_change->SetRevertValueFrom(change);
   return true;
 }
 
 void WindowTreeClient::BuildWindowTree(
-    const mojo::Array<ui::mojom::WindowDataPtr>& windows,
-    WindowMus* initial_parent) {
-  std::vector<WindowMus*> parents;
-  WindowMus* last_window = nullptr;
-  if (initial_parent)
-    parents.push_back(initial_parent);
+    const mojo::Array<ui::mojom::WindowDataPtr>& windows) {
   for (const auto& window_data : windows) {
-    if (last_window && window_data->parent_id == last_window->server_id()) {
-      parents.push_back(last_window);
-    } else if (!parents.empty()) {
-      while (parents.back()->server_id() != window_data->parent_id)
-        parents.pop_back();
-    }
-    // This code is only called in a context where there is a parent.
-    DCHECK(!parents.empty());
-    last_window = NewWindowFromWindowData(
-        !parents.empty() ? parents.back() : nullptr, window_data);
+    WindowMus* parent = window_data->parent_id == kInvalidServerId
+                            ? nullptr
+                            : GetWindowByServerId(window_data->parent_id);
+    WindowMus* existing_window = GetWindowByServerId(window_data->window_id);
+    if (!existing_window)
+      NewWindowFromWindowData(parent, window_data);
+    else if (parent)
+      parent->AddChildFromServer(existing_window);
   }
 }
 
 std::unique_ptr<WindowPortMus> WindowTreeClient::CreateWindowPortMus(
     const ui::mojom::WindowDataPtr& window_data,
     WindowMusType window_mus_type) {
   std::unique_ptr<WindowPortMus> window_port_mus(
       base::MakeUnique<WindowPortMus>(this, window_mus_type));
   window_port_mus->set_server_id(window_data->window_id);
   RegisterWindowMus(window_port_mus.get());
@@ skipping 632 matching lines @@
   // with an in flight delete from the server.
   if (window && transient_window)
     window->RemoveTransientChildFromServer(transient_window);
 }
 
 void WindowTreeClient::OnWindowHierarchyChanged(
     Id window_id,
     Id old_parent_id,
     Id new_parent_id,
     mojo::Array<ui::mojom::WindowDataPtr> windows) {
-  WindowMus* initial_parent =
-      windows.size() ? GetWindowByServerId(windows[0]->parent_id) : nullptr;
-
   const bool was_window_known = GetWindowByServerId(window_id) != nullptr;
 
-  BuildWindowTree(windows, initial_parent);
+  BuildWindowTree(windows);
 
   // If the window was not known, then BuildWindowTree() will have created it
   // and parented the window.
   if (!was_window_known)
     return;
 
   WindowMus* new_parent = GetWindowByServerId(new_parent_id);
   WindowMus* old_parent = GetWindowByServerId(old_parent_id);
   WindowMus* window = GetWindowByServerId(window_id);
   if (new_parent)
@@ skipping 549 matching lines @@
   return ScheduleInFlightChange(
       base::MakeUnique<InFlightDragChange>(window, ChangeType::DRAG_LOOP));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForCapture(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 }  // namespace aura