chromeos: wires transients using the WindowTreeHost window

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 254 matching lines @@
   // renders to.
   content_window->layer()->SetFillsBoundsOpaquely(false);
   if (!params.bounds.IsEmpty())
     SetBoundsInDIP(params.bounds);
 
   cursor_manager_ = base::MakeUnique<wm::CursorManager>(
       base::MakeUnique<NativeCursorManagerMus>(window()));
   aura::client::SetCursorClient(window(), cursor_manager_.get());
   InitHost();
 
-  if (params.parent) {
-    aura::client::GetTransientWindowClient()->AddTransientChild(params.parent,
-                                                                window());
+  // Transient parents are connected using the Window created by WindowTreeHost,
+  // which is owned by the window manager. This way the window manager can
+  // properly identify and honor transients.
+  if (params.parent && params.parent->GetHost()) {
+    aura::client::GetTransientWindowClient()->AddTransientChild(
+        params.parent->GetHost()->window(), window());
   }
 }
 
 void DesktopWindowTreeHostMus::OnNativeWidgetCreated(
     const Widget::InitParams& params) {
   if (params.parent && params.parent->GetHost()) {
     parent_ = static_cast<DesktopWindowTreeHostMus*>(params.parent->GetHost());
     parent_->children_.insert(this);
   }
   native_widget_delegate_->OnNativeWidgetCreated(true);
@@ skipping 438 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