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 {
+
+class WindowTreeDataExternal : public WindowTreeData {

[kylechar, 2017/02/21 18:51:08]

WindowTreeDataExternal + kSquareSize should be in an anonymous namespace.

[fwang, 2017/02/21 19:02:21]

Done.

+ 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));
+  }
+
+  // Holds the Mojo pointer to the window tree host.
+  mojom::WindowTreeHostPtr host_;

[fwang, 2017/02/21 17:44:17]

Oops, missing private here :-( Will take care of it in the next iteration...

[fwang, 2017/02/21 19:02:21]

Done.

+};
+
+// Size of square in pixels to draw.
+const int kSquareSize = 500;
+
+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->reset(new aura::WindowTreeClient(

[kylechar, 2017/02/21 18:51:08]

Do something like the following for these?

*window_tree_client = base::MakeUnique<aura::WindowTreeClient>(...);

[fwang, 2017/02/21 19:02:21]

Mmh, not sure what it did not work when I initially tried. Done now.

+      context()->connector(), this, nullptr, MakeRequest(&tree_client)));
+  // TODO(tonikitoo,fwang): Open two external windows with different square
+  // sizes.
+  window_tree_data->reset(new 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().
+  fake_display_ = base::MakeUnique<display::Display>(0);

[kylechar, 2017/02/21 18:51:08]

|fake_display_| doesn't need to be a member variable or unique_ptr. You can just
make display::Display here and pass it AddPrimaryDisplay(). It gets copied there
and won't be needed after.

[fwang, 2017/02/21 19:02:21]

Done.

+  AddPrimaryDisplay(*fake_display_);
+}
+
+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