Allow parallel creation of windows

services/ui/demo/mus_demo_internal.cc

 // Copyright 2017 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/demo/mus_demo_internal.h"
 
 #include "services/service_manager/public/cpp/service_context.h"
 #include "services/ui/demo/window_tree_data.h"
 #include "ui/aura/mus/window_tree_client.h"
 #include "ui/aura/mus/window_tree_host_mus.h"
 
 namespace ui {
 namespace demo {
 
 namespace {
 
+class WindowTreeDataInternal : public WindowTreeData {
+ public:
+  // Creates a new window tree host associated to the WindowTreeData.
+  WindowTreeDataInternal(
+      std::unique_ptr<aura::WindowTreeHostMus> window_tree_host,
+      int square_size)
+      : WindowTreeData(square_size) {
+    DCHECK(window_tree_host);
+    window_tree_host->InitHost();
+    window_tree_host->Show();
+    SetWindowTreeHost(std::move(window_tree_host));
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(WindowTreeDataInternal);
+};
+
 // Size of square in pixels to draw.
 const int kSquareSize = 300;
 }
 
 MusDemoInternal::MusDemoInternal() {}
 
 MusDemoInternal::~MusDemoInternal() {}
 
 std::unique_ptr<aura::WindowTreeClient>
 MusDemoInternal::CreateWindowTreeClient() {
@@ skipping 36 matching lines @@
   // Don't care
 }
 
 void MusDemoInternal::OnWmWillCreateDisplay(const display::Display& display) {
   AddPrimaryDisplay(display);
 }
 
 void MusDemoInternal::OnWmNewDisplay(
     std::unique_ptr<aura::WindowTreeHostMus> window_tree_host,
     const display::Display& display) {
-  AppendWindowTreeData(base::MakeUnique<WindowTreeData>(kSquareSize));
-  InitWindowTreeData(std::move(window_tree_host));
+  std::unique_ptr<WindowTreeDataInternal> window_tree_data =
+      base::MakeUnique<WindowTreeDataInternal>(std::move(window_tree_host),
+                                               kSquareSize);
+  window_tree_data->Init();
+  AppendWindowTreeData(std::move(window_tree_data));
 }
 
 void MusDemoInternal::OnWmDisplayRemoved(
     aura::WindowTreeHostMus* window_tree_host) {
   RemoveWindowTreeData(window_tree_host);
 }
 
 void MusDemoInternal::OnWmDisplayModified(const display::Display& display) {}
 
 mojom::EventResult MusDemoInternal::OnAccelerator(uint32_t id,
@@ skipping 17 matching lines @@
     const std::vector<gfx::Rect>& additional_client_areas) {}
 
 bool MusDemoInternal::IsWindowActive(aura::Window* window) {
   return false;
 }
 
 void MusDemoInternal::OnWmDeactivateWindow(aura::Window* window) {}
 
 }  // namespace demo
 }  // namespace ui