Mus Demo: Refactor code to prepare multiple windows in external mode

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 {
 
 // Size of square in pixels to draw.
 const int kSquareSize = 300;
 }
 
 MusDemoInternal::MusDemoInternal() {}
 
 MusDemoInternal::~MusDemoInternal() {}
 
-void MusDemoInternal::OnStartImpl(
-    std::unique_ptr<aura::WindowTreeClient>* window_tree_client,
-    std::unique_ptr<WindowTreeData>* window_tree_data) {
-  *window_tree_client = base::MakeUnique<aura::WindowTreeClient>(
-      context()->connector(), this, this);
-  window_tree_client->get()->ConnectAsWindowManager();
-  *window_tree_data = base::MakeUnique<WindowTreeData>(kSquareSize);
+std::unique_ptr<aura::WindowTreeClient>
+MusDemoInternal::CreateWindowTreeClient() {
+  return base::MakeUnique<aura::WindowTreeClient>(context()->connector(), this,
+                                                  this);
+}
+
+void MusDemoInternal::OnStartImpl() {
+  window_tree_client()->ConnectAsWindowManager();
+  // The demo will actually start when the window server creates the display,
+  // causing OnWmNewDisplay to be called.
 }
 
 void MusDemoInternal::SetWindowManagerClient(
     aura::WindowManagerClient* client) {}
 
 bool MusDemoInternal::OnWmSetBounds(aura::Window* window, gfx::Rect* bounds) {
   return true;
 }
 
 bool MusDemoInternal::OnWmSetProperty(
@@ skipping 18 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));
 }
 
 void MusDemoInternal::OnWmDisplayRemoved(
     aura::WindowTreeHostMus* window_tree_host) {
-  CleanupWindowTreeData();
+  RemoveWindowTreeData(window_tree_host);
 }
 
 void MusDemoInternal::OnWmDisplayModified(const display::Display& display) {}
 
 mojom::EventResult MusDemoInternal::OnAccelerator(uint32_t id,
                                                   const Event& event) {
   return mojom::EventResult::UNHANDLED;
 }
 
 void MusDemoInternal::OnWmPerformMoveLoop(
@@ skipping 12 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