chromeos: Fix shelf appearing at login screen under mash

ash/mus/window_manager.cc

Index: ash/mus/window_manager.cc
diff --git a/ash/mus/window_manager.cc b/ash/mus/window_manager.cc
index 221df659414427fad02fb2dd44fa294c3c033b79..5e1c8c9dcf2d0f61cd5b25501725f34461b007f5 100644
--- a/ash/mus/window_manager.cc
+++ b/ash/mus/window_manager.cc
@@ -8,6 +8,7 @@
 
 #include <utility>
 
+#include "ash/common/session/session_controller.h"
 #include "ash/common/wm/container_finder.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/display/screen_position_controller.h"
@@ -137,9 +138,6 @@ void WindowManager::Init(
                               this, pointer_watcher_event_router_.get()));
   shell_->Initialize(blocking_pool);
   lookup_.reset(new WmLookupMus);
-
-  // TODO: this should be called when logged in. See http://crbug.com/654606.
-  shell_->CreateShelf();
 }
 
 aura::Window* WindowManager::NewTopLevelWindow(
@@ -221,8 +219,9 @@ RootWindowController* WindowManager::CreateRootWindowController(
       root_window_controller_ptr.get();
   root_window_controllers_.insert(std::move(root_window_controller_ptr));
 
-  // TODO: this should be called when logged in. See http://crbug.com/654606.
-  root_window_controller->wm_root_window_controller()->CreateShelf();
+  // Create a shelf if a user is already logged in.
+  if (shell_->session_controller()->NumberOfLoggedInUsers())
+    root_window_controller->wm_root_window_controller()->CreateShelf();
 
   for (auto& observer : observers_)
     observer.OnRootWindowControllerAdded(root_window_controller);