DesktopAura: Track windows "owned" via the DesktopWindowTreeHost

ui/views/mus/desktop_window_tree_host_mus.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/views/mus/desktop_window_tree_host_mus.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/cursor_client.h"
@@ skipping 260 matching lines @@
       base::MakeUnique<NativeCursorManagerMus>(window()));
   aura::client::SetCursorClient(window(), cursor_manager_.get());
   InitHost();
 }
 
 void DesktopWindowTreeHostMus::OnNativeWidgetCreated(
     const Widget::InitParams& params) {
   if (params.parent && params.parent->GetHost()) {
     parent_ = static_cast<DesktopWindowTreeHostMus*>(params.parent->GetHost());
     parent_->children_.insert(this);
+    wm::AddTransientChild(params.parent, window());
   }
   native_widget_delegate_->OnNativeWidgetCreated(true);
 }
 
 void DesktopWindowTreeHostMus::OnNativeWidgetActivationChanged(bool active) {
   // In Mus, when our aura Window receives an activation signal, it can be
   // because of remote messages. We need to forward that to Widget so that
   // Widget can notify everyone listening for that signal.
   native_widget_delegate_->OnNativeWidgetActivationChanged(active);
 }
@@ skipping 437 matching lines @@
     aura::client::FocusClient* focus_client,
     aura::Window* window) {
   if (window == this->window()) {
     desktop_native_widget_aura_->HandleActivationChanged(true);
   } else if (is_active_) {
     desktop_native_widget_aura_->HandleActivationChanged(false);
   }
 }
 
 }  // namespace views