Fixes aura unit tests. There were a couple of problems:

ui/aura/desktop.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/desktop.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "ui/aura/desktop_host.h"
 #include "ui/aura/root_window.h"
+#include "ui/aura/toplevel_window_container.h"
 #include "ui/aura/window.h"
 #include "ui/gfx/compositor/compositor.h"
 #include "ui/gfx/compositor/layer.h"
 
 namespace aura {
 
 // static
 Desktop* Desktop::instance_ = NULL;
 
 Desktop::Desktop()
-    : toplevel_window_container_(NULL),
+    : toplevel_window_container_(new aura::internal::ToplevelWindowContainer),
       host_(aura::DesktopHost::Create(gfx::Rect(200, 200, 1280, 1024))),
       ALLOW_THIS_IN_INITIALIZER_LIST(schedule_paint_(this)) {
   DCHECK(MessageLoopForUI::current())
       << "The UI message loop must be initialized first.";
   compositor_ = ui::Compositor::Create(this, host_->GetAcceleratedWidget(),
                                        host_->GetSize());
   host_->SetDesktop(this);
   DCHECK(compositor_.get());
   window_.reset(new internal::RootWindow);
 }
 
 Desktop::~Desktop() {
   if (instance_ == this)
     instance_ = NULL;
 }
 
 void Desktop::Init() {
   window_->Init();
   compositor()->set_root_layer(window_->layer());
+  toplevel_window_container_->Init();
+  toplevel_window_container_->SetBounds(gfx::Rect(0, 0, 1280, 1024), 0);
+  toplevel_window_container_->SetVisibility(aura::Window::VISIBILITY_SHOWN);
+  toplevel_window_container_->SetParent(window_.get());
 #if defined(USE_X11)
   // TODO(oshima): Implement configure notify and remove this.
   OnHostResized(host_->GetSize());
 #endif
 }
 
 void Desktop::Show() {
   host_->Show();
 }
 
@@ skipping 34 matching lines @@
 // static
 Desktop* Desktop::GetInstance() {
   if (!instance_) {
     instance_ = new Desktop;
     instance_->Init();
   }
   return instance_;
 }
 
 }  // namespace aura