reland of https://codereview.chromium.org/11364053/ w/o removing the per-rootwindow stacking client

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 82 matching lines @@
   explicit DemoStackingClient(aura::RootWindow* root_window)
       : root_window_(root_window) {
     aura::client::SetStackingClient(this);
   }
 
   virtual ~DemoStackingClient() {
     aura::client::SetStackingClient(NULL);
   }
 
   // Overridden from aura::client::StackingClient:
-  virtual aura::Window* GetDefaultParent(aura::Window* window,
+  virtual aura::Window* GetDefaultParent(aura::Window* context,
+                                         aura::Window* window,
                                          const gfx::Rect& bounds) OVERRIDE {
     if (!capture_client_.get()) {
       capture_client_.reset(
           new aura::client::DefaultCaptureClient(root_window_));
     }
     return root_window_;
   }
 
  private:
   aura::RootWindow* root_window_;
@@ skipping 53 matching lines @@
 
   // 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();
 }