Revert of chromeos: Makes mushrome use simplified display management

chrome/browser/ui/ash/ash_init.cc

Index: chrome/browser/ui/ash/ash_init.cc
diff --git a/chrome/browser/ui/ash/ash_init.cc b/chrome/browser/ui/ash/ash_init.cc
index ad86e760b562c589fb7d550151607bd3d85dff15..5ce632f3d27b251765965c50bfc9083612453a7f 100644
--- a/chrome/browser/ui/ash/ash_init.cc
+++ b/chrome/browser/ui/ash/ash_init.cc
@@ -65,10 +65,8 @@
 std::unique_ptr<ash::mus::WindowManager> CreateMusShell() {
   service_manager::Connector* connector =
       content::ServiceManagerConnection::GetForProcess()->GetConnector();
-  const bool show_primary_host_on_connect = true;
   std::unique_ptr<ash::mus::WindowManager> window_manager =
-      base::MakeUnique<ash::mus::WindowManager>(connector, ash::Config::MUS,
-                                                show_primary_host_on_connect);
+      base::MakeUnique<ash::mus::WindowManager>(connector, ash::Config::MUS);
   // The WindowManager normally deletes the Shell when it loses its connection
   // to mus. Disable that by installing an empty callback. Chrome installs
   // its own callback to detect when the connection to mus is lost and that is
@@ -77,9 +75,7 @@
   std::unique_ptr<aura::WindowTreeClient> window_tree_client =
       base::MakeUnique<aura::WindowTreeClient>(connector, window_manager.get(),
                                                window_manager.get());
-  const bool automatically_create_display_roots = false;
-  window_tree_client->ConnectAsWindowManager(
-      automatically_create_display_roots);
+  window_tree_client->ConnectAsWindowManager();
   aura::Env::GetInstance()->SetWindowTreeClient(window_tree_client.get());
   window_manager->Init(std::move(window_tree_client),
                        content::BrowserThread::GetBlockingPool(),