Desktop aura: Break aura::Window::SetParent in two.

ui/aura/demo/demo_main.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 "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/i18n/icu_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "third_party/skia/include/core/SkXfermode.h"
@@ skipping 119 matching lines @@
   scoped_ptr<DemoStackingClient> stacking_client(new DemoStackingClient(
       root_window.get()));
 
   // Create a hierarchy of test windows.
   DemoWindowDelegate window_delegate1(SK_ColorBLUE);
   aura::Window window1(&window_delegate1);
   window1.set_id(1);
   window1.Init(ui::LAYER_TEXTURED);
   window1.SetBounds(gfx::Rect(100, 100, 400, 400));
   window1.Show();
-  window1.SetParent(NULL);
+  window1.SetDefaultParentByTargetRoot(root_window.get(), gfx::Rect());
 
   DemoWindowDelegate window_delegate2(SK_ColorRED);
   aura::Window window2(&window_delegate2);
   window2.set_id(2);
   window2.Init(ui::LAYER_TEXTURED);
   window2.SetBounds(gfx::Rect(200, 200, 350, 350));
   window2.Show();
-  window2.SetParent(NULL);
+  window2.SetDefaultParentByTargetRoot(root_window.get(), gfx::Rect());
 
   DemoWindowDelegate window_delegate3(SK_ColorGREEN);
   aura::Window window3(&window_delegate3);
   window3.set_id(3);
   window3.Init(ui::LAYER_TEXTURED);
   window3.SetBounds(gfx::Rect(10, 10, 50, 50));
   window3.Show();
-  window3.SetParent(&window2);
+  window2.AddChild(&window3);
 
   root_window->ShowRootWindow();
   MessageLoopForUI::current()->Run();
 
   ui::CompositorTestSupport::Terminate();
 
   return 0;
 }
 
 }  // namespace
 
 int main(int argc, char** argv) {
   CommandLine::Init(argc, argv);
 
   // The exit manager is in charge of calling the dtors of singleton objects.
   base::AtExitManager exit_manager;
 
   ui::RegisterPathProvider();
   icu_util::Initialize();
   ResourceBundle::InitSharedInstanceWithLocale("en-US", NULL);
 
   return DemoMain();
 }