Gets chrome --mus some what working

ui/aura/mus/window_tree_client.h

Index: ui/aura/mus/window_tree_client.h
diff --git a/ui/aura/mus/window_tree_client.h b/ui/aura/mus/window_tree_client.h
index ce6ca6357e965249bc09fb07f9667294faf45e9a..da80da9207f1cf64ab1640a19231d0655d2942c5 100644
--- a/ui/aura/mus/window_tree_client.h
+++ b/ui/aura/mus/window_tree_client.h
@@ -456,6 +456,7 @@ class AURA_EXPORT WindowTreeClient
   void ActivateNextWindow() override;
   void SetExtendedHitArea(Window* window, const gfx::Insets& hit_area) override;
   void RequestClose(Window* window) override;
+  bool WaitForInitialDisplays() override;
 
   // Overriden from WindowTreeHostMusDelegate:
   void OnWindowTreeHostBoundsWillChange(WindowTreeHostMus* window_tree_host,
@@ -588,6 +589,10 @@ class AURA_EXPORT WindowTreeClient
   // If |compositor_context_factory_| is installed on Env, then this is the
   // ContextFactory that was set on Env originally.
   ui::ContextFactory* initial_context_factory_ = nullptr;
+
+  // Set to true once OnWmDisplayAdded() is called.
+  bool got_initial_displays_ = false;
+
   base::WeakPtrFactory<WindowTreeClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClient);