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

ui/aura/window.h

Index: ui/aura/window.h
diff --git a/ui/aura/window.h b/ui/aura/window.h
index ccfdc4810d599015a1f0280a9429b8fe033a984b..c6208129fed96f9b1ebdde3ddaa810064e081be0 100644
--- a/ui/aura/window.h
+++ b/ui/aura/window.h
@@ -171,9 +171,10 @@ class AURA_EXPORT Window : public ui::LayerDelegate,
   // Assigns a new external texture to the window's layer.
   void SetExternalTexture(ui::Texture* texture);
 
-  // Sets the parent window of the window. If NULL, the window is parented to
-  // the root window.
-  void SetParent(Window* parent);
+  // Places this window where |target_root| specifies. |target_root| may not be
+  // NULL.
+  void SetDefaultParentByTargetRoot(RootWindow* target_root,

[sky, 2012/11/21 23:35:59]

nit: TargetRoot doesn't mean much, how about SetDefaultParentByRoot or
SetDefaultParentInRoot. Also, clarify the coordinates of |bounds|.

+                                    const gfx::Rect& bounds);
 
   // Stacks the specified child of this Window at the front of the z-order.
   void StackChildAtTop(Window* child);