c++ / mojo changes for 'external window mode'

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index 0f7351c738917443789d004d657cba9e57e89b8b..2bd5bd0e68793ef56159267a76bdd8891c05e25c 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -226,6 +226,20 @@ void WindowTreeClient::ConnectViaWindowTreeFactory() {
   SetWindowTree(std::move(window_tree));
 }
 
+void WindowTreeClient::ConnectViaWindowTreeHostFactory() {
+  // The client id doesn't really matter, we use 101 purely for debugging.
+  client_id_ = 101;
+
+  ui::mojom::WindowTreeHostFactoryRegistrarPtr host_factory_registrar;
+  connector_->BindInterface(ui::mojom::kServiceName, &host_factory_registrar);
+
+  ui::mojom::WindowTreePtr window_tree;
+  host_factory_registrar->Register(MakeRequest(&window_tree_host_factory_ptr_),
+                                   MakeRequest(&window_tree),
+                                   binding_.CreateInterfacePtrAndBind());
+  SetWindowTree(std::move(window_tree));
+}
+
 void WindowTreeClient::ConnectAsWindowManager() {
   DCHECK(window_manager_delegate_);
 
@@ -237,6 +251,10 @@ void WindowTreeClient::ConnectAsWindowManager() {
   SetWindowTree(std::move(window_tree));
 }
 
+void WindowTreeClient::CreateHost(ui::mojom::WindowTreeHostRequest host) {
+  window_tree_host_factory_ptr_->CreateWindowTreeHost(std::move(host));
+}
+
 void WindowTreeClient::SetCanFocus(Window* window, bool can_focus) {
   DCHECK(tree_);
   DCHECK(window);
@@ -505,7 +523,6 @@ void WindowTreeClient::OnEmbedImpl(ui::mojom::WindowTree* window_tree,
   client_id_ = client_id;
   WindowTreeConnectionEstablished(window_tree);
 
-  DCHECK(roots_.empty());
   std::unique_ptr<WindowTreeHostMus> window_tree_host =
       CreateWindowTreeHost(WindowMusType::EMBED, *root_data, display_id);
 
@@ -839,8 +856,13 @@ void WindowTreeClient::OnEmbed(ClientSpecificId client_id,
                                int64_t display_id,
                                Id focused_window_id,
                                bool drawn) {
-  DCHECK(!tree_ptr_);
-  tree_ptr_ = std::move(tree);
+  // No need to set 'tree_ptr_' whether it was already set during
+  // ConnectViaWindowManagerHostFactory.
+  DCHECK((tree_ptr_ && !tree) || (!tree_ptr_ && tree));
+  if (tree) {
+    DCHECK(roots_.empty());
+    tree_ptr_ = std::move(tree);
+  }
 
   is_from_embed_ = true;