chromeos: Makes mushrome use simplified display management

ash/mus/window_manager.h

Index: ash/mus/window_manager.h
diff --git a/ash/mus/window_manager.h b/ash/mus/window_manager.h
index 8f8631b130d1f85b0c49c0f0e3341d0a24a8cc75..84bb75f6b0985fe880f278558bbd2ad01fe66cb8 100644
--- a/ash/mus/window_manager.h
+++ b/ash/mus/window_manager.h
@@ -68,7 +68,11 @@ class WmTestHelper;
 class WindowManager : public aura::WindowManagerDelegate,
                       public aura::WindowTreeClientDelegate {
  public:
-  WindowManager(service_manager::Connector* connector, Config config);
+  // Set |show_primary_host_on_connect| to true if the initial display should
+  // be made visible.  Generally tests should use false, other places use true.
+  WindowManager(service_manager::Connector* connector,
+                Config config,
+                bool show_primary_host_on_connect);
   ~WindowManager() override;
 
   void Init(std::unique_ptr<aura::WindowTreeClient> window_tree_client,
@@ -202,6 +206,8 @@ class WindowManager : public aura::WindowManagerDelegate,
 
   const Config config_;
 
+  const bool show_primary_host_on_connect_;
+
   base::OnceClosure lost_connection_callback_;
 
   std::unique_ptr<::wm::WMState> wm_state_;