Mus Demo: Demonstrate external window mode

services/ui/demo/mus_demo_external.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_external.h"
+
+#include "services/service_manager/public/cpp/service_context.h"
+#include "services/ui/demo/window_tree_data.h"
+#include "services/ui/public/interfaces/constants.mojom.h"
+#include "services/ui/public/interfaces/window_tree_host.mojom.h"
+#include "ui/aura/mus/window_tree_client.h"
+#include "ui/aura/mus/window_tree_host_mus.h"
+#include "ui/display/display.h"
+
+namespace ui {
+namespace demo {
+
+namespace {
+
+class WindowTreeDataExternal : public WindowTreeData {
+ public:
+  // Creates a new window tree host associated to the WindowTreeData.
+  WindowTreeDataExternal(mojom::WindowTreeHostFactory* factory,
+                         mojom::WindowTreeClientPtr tree_client,
+                         int square_size)
+      : WindowTreeData(square_size) {
+    factory->CreateWindowTreeHost(MakeRequest(&host_), std::move(tree_client));
+  }
+
+ private:
+  // Holds the Mojo pointer to the window tree host.
+  mojom::WindowTreeHostPtr host_;
+};
+
+// Size of square in pixels to draw.
+const int kSquareSize = 500;
+}  // namespace
+
+MusDemoExternal::MusDemoExternal() {}
+
+MusDemoExternal::~MusDemoExternal() {}
+
+void MusDemoExternal::OnStartImpl(
+    std::unique_ptr<aura::WindowTreeClient>* window_tree_client,
+    std::unique_ptr<WindowTreeData>* window_tree_data) {
+  context()->connector()->BindInterface(ui::mojom::kServiceName,
+                                        &window_tree_host_factory_);
+  mojom::WindowTreeClientPtr tree_client;
+  *window_tree_client = base::MakeUnique<aura::WindowTreeClient>(
+      context()->connector(), this, nullptr, MakeRequest(&tree_client));
+  // TODO(tonikitoo,fwang): Open two external windows with different square
+  // sizes.
+  *window_tree_data = base::MakeUnique<WindowTreeDataExternal>(
+      window_tree_host_factory_.get(), std::move(tree_client), kSquareSize);
+
+  // TODO(tonikitoo,fwang): Implement management of displays in external mode.
+  // For now, a fake display is created in order to work around an assertion in
+  // aura::GetDeviceScaleFactorFromDisplay().
+  AddPrimaryDisplay(display::Display(0));
+}
+
+void MusDemoExternal::OnEmbed(
+    std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) {
+  InitWindowTreeData(std::move(window_tree_host));
+}
+
+void MusDemoExternal::OnEmbedRootDestroyed(
+    aura::WindowTreeHostMus* window_tree_host) {
+  CleanupWindowTreeData();
+}
+
+}  // namespace demo
+}  // namespace ui