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

ui/aura/test/test_windows.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_WINDOWS_H_
 #define UI_AURA_TEST_TEST_WINDOWS_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/aura/client/window_types.h"
 #include "ui/aura/test/test_window_delegate.h"
 #include "ui/aura/test/aura_test_base.h"
 
 namespace aura {
 namespace test {
 
+// These functions expect a non-NULL parent. If you want to let the
+// StackingClient determine where to place the windows, there are equivalent
+// methods in AshTestBase.
 Window* CreateTestWindowWithId(int id, Window* parent);
 Window* CreateTestWindowWithBounds(const gfx::Rect& bounds, Window* parent);
 Window* CreateTestWindow(SkColor color,
                          int id,
                          const gfx::Rect& bounds,
                          Window* parent);
 Window* CreateTestWindowWithDelegate(WindowDelegate* delegate,
                                      int id,
                                      const gfx::Rect& bounds,
                                      Window* parent);
 Window* CreateTestWindowWithDelegateAndType(WindowDelegate* delegate,
                                             client::WindowType type,
                                             int id,
                                             const gfx::Rect& bounds,
                                             Window* parent);
 
-// Creates a transient child window of |parent|.
-Window* CreateTransientChild(int id, Window* parent);
-
 // Returns true if |upper| is above |lower| in the window stacking order.
 bool WindowIsAbove(Window* upper, Window* lower);
 
 // Returns true if |upper|'s layer is above |lower|'s layer in the layer
 // stacking order.
 bool LayerIsAbove(Window* upper, Window* lower);
 
 // Returns a string containing the id of each of the child windows (bottommost
 // first) of |parent|. The format of the string is "id1 id2 id...".
 std::string ChildWindowIDsAsString(aura::Window* parent);
 
 }  // namespace test
 }  // namespace aura
 
 #endif  // UI_AURA_TEST_TEST_WINDOWS_H_