Use WindowTracker when resizing root window as it may delete other window in unit tests.

ui/aura/test/test_windows.cc

Index: ui/aura/test/test_windows.cc
diff --git a/ui/aura/test/test_windows.cc b/ui/aura/test/test_windows.cc
index 50f831585abe47607a6a9f8d03b9dc607698cfae..141510a3dc778776f66630c3486f6b5b0830a247 100644
--- a/ui/aura/test/test_windows.cc
+++ b/ui/aura/test/test_windows.cc
@@ -46,11 +46,11 @@ Window* CreateTestWindowWithDelegateAndType(WindowDelegate* delegate,
   window->set_id(id);
   window->SetType(type);
   window->Init(ui::LAYER_TEXTURED);
+  window->SetProperty(aura::client::kCanMaximizeKey, true);
   window->SetBounds(bounds);
   window->Show();
   if (parent)
     parent->AddChild(window);
-  window->SetProperty(aura::client::kCanMaximizeKey, true);
   return window;
 }