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

ui/aura/test/test_windows.cc

 // Copyright (c) 2012 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/test/test_windows.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
@@ skipping 28 matching lines @@
 
 Window* CreateTestWindowWithDelegateAndType(WindowDelegate* delegate,
                                             ui::wm::WindowType type,
                                             int id,
                                             const gfx::Rect& bounds,
                                             Window* parent) {
   Window* window = new Window(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;
 }
 
 template <typename T>
 bool ObjectIsAbove(T* upper, T* lower) {
   DCHECK_EQ(upper->parent(), lower->parent());
   DCHECK_NE(upper, lower);
   const std::vector<T*>& children = upper->parent()->children();
   const size_t upper_i =
       std::find(children.begin(), children.end(), upper) - children.begin();
@@ skipping 16 matching lines @@
        i != parent->children().end(); ++i) {
     if (!result.empty())
       result += " ";
     result += base::IntToString((*i)->id());
   }
   return result;
 }
 
 }  // namespace test
 }  // namespace aura