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

ui/aura/test/test_stacking_client.h

 // 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.
 
 #ifndef UI_AURA_TEST_TEST_STACKING_CLIENT_H_
 #define UI_AURA_TEST_TEST_STACKING_CLIENT_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/aura/aura_export.h"
 #include "ui/aura/client/stacking_client.h"
 
 namespace aura {
 class RootWindow;
 namespace test {
 
 class TestStackingClient : public client::StackingClient {
  public:
   explicit TestStackingClient(RootWindow* root_window);
   virtual ~TestStackingClient();
 
   // Overridden from client::StackingClient:
-  virtual Window* GetDefaultParent(Window* window,
+  virtual Window* GetDefaultParent(Window* context,
+                                   Window* window,
                                    const gfx::Rect& bounds) OVERRIDE;
 
  private:
   RootWindow* root_window_;
 
   DISALLOW_COPY_AND_ASSIGN(TestStackingClient);
 };
 
 }  // namespace test
 }  // namespace aura
 
 #endif  // UI_AURA_TEST_TEST_STACKING_CLIENT_H_