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

services/ui/demo/mus_demo.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 "services/ui/demo/mus_demo.h"
 
 #include "base/memory/ptr_util.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/ui/demo/window_tree_data.h"
 #include "services/ui/public/cpp/gpu/gpu.h"
@@ skipping 13 matching lines @@
 
 MusDemo::~MusDemo() {
   display::Screen::SetScreenInstance(nullptr);
 }
 
 void MusDemo::AddPrimaryDisplay(const display::Display& display) {
   screen_->display_list().AddDisplay(display,
                                      display::DisplayList::Type::PRIMARY);
 }
 
+bool MusDemo::HasPendingWindowTreeData() const {
+  return !window_tree_data_list_.empty() &&
+         !window_tree_data_list_.back()->IsInitialized();
+}
+
+void MusDemo::AppendWindowTreeData(
+    std::unique_ptr<WindowTreeData> window_tree_data) {
+  DCHECK(!HasPendingWindowTreeData());
+  window_tree_data_list_.push_back(std::move(window_tree_data));
+}
+
 void MusDemo::InitWindowTreeData(
     std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) {
-  DCHECK(window_tree_data_);
-  DCHECK(!window_tree_data_->IsInitialized());
-  window_tree_data_->Init(std::move(window_tree_host));
+  DCHECK(HasPendingWindowTreeData());
+  window_tree_data_list_.back()->Init(std::move(window_tree_host));
 }
 
-void MusDemo::CleanupWindowTreeData() {
-  window_tree_data_.reset();
+void MusDemo::RemoveWindowTreeData(aura::WindowTreeHostMus* window_tree_host) {
+  DCHECK(window_tree_host);
+  auto it =
+      std::find_if(window_tree_data_list_.begin(), window_tree_data_list_.end(),
+                   [window_tree_host](std::unique_ptr<WindowTreeData>& data) {
+                     return data->WindowTreeHost() == window_tree_host;
+                   });
+  DCHECK(it != window_tree_data_list_.end());
+  window_tree_data_list_.erase(it);
 }
 
 void MusDemo::OnStart() {
   screen_ = base::MakeUnique<display::ScreenBase>();
   display::Screen::SetScreenInstance(screen_.get());
 
   env_ = aura::Env::CreateInstance(aura::Env::Mode::MUS);
   capture_client_ = base::MakeUnique<aura::client::DefaultCaptureClient>();
   property_converter_ = base::MakeUnique<aura::PropertyConverter>();
   wm_state_ = base::MakeUnique<::wm::WMState>();
 
-  OnStartImpl(&window_tree_client_, &window_tree_data_);
+  window_tree_client_ = CreateWindowTreeClient();
+  OnStartImpl();
 
   env_->SetWindowTreeClient(window_tree_client_.get());
 }
 
 bool MusDemo::OnConnect(const service_manager::ServiceInfo& remote_info,
                         service_manager::InterfaceRegistry* registry) {
   return true;
 }
 
 void MusDemo::OnEmbed(
     std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) {
   NOTREACHED();
 }
 
 void MusDemo::OnUnembed(aura::Window* root) {
   NOTREACHED();
 }
 
 void MusDemo::OnEmbedRootDestroyed(aura::WindowTreeHostMus* window_tree_host) {
   NOTREACHED();
 }
 
 void MusDemo::OnLostConnection(aura::WindowTreeClient* client) {
   window_tree_client_.reset();
-  CleanupWindowTreeData();
+  window_tree_data_list_.clear();
 }
 
 void MusDemo::OnPointerEventObserved(const PointerEvent& event,
                                      aura::Window* target) {}
 
 aura::PropertyConverter* MusDemo::GetPropertyConverter() {
   return property_converter_.get();
 }
 
 }  // namespace demo
 }  // namespace ui