Fixes bug in handling restacking because of transients

ui/aura/client/transient_window_client_observer.h

Index: ui/aura/client/transient_window_client_observer.h
diff --git a/ui/aura/client/transient_window_client_observer.h b/ui/aura/client/transient_window_client_observer.h
index 27dc39bf44a404750ccdee1666beb2513863b837..bb7176dc1d361cb83a0d0881756f1097e039b46f 100644
--- a/ui/aura/client/transient_window_client_observer.h
+++ b/ui/aura/client/transient_window_client_observer.h
@@ -25,6 +25,15 @@ class AURA_EXPORT TransientWindowClientObserver {
   virtual void OnTransientChildWindowRemoved(Window* parent,
                                              Window* transient_child) = 0;
 
+  // Called when adding or removing a transient results in restacking. |window|
+  // is the window being stacked above |source|. |source| is the window the
+  // transient was added or removed from. This is followed by a call to
+  // Window::StackChildAbove() and then OnDidRestackTransientChildAbove().
+  virtual void OnWillRestackTransientChildAbove(Window* source,

[msw, 2016/11/21 19:56:33]

nit: are there better names we can use here? like |parent| and |transient_child|
above?

[sky, 2016/11/21 21:31:43]

Done.

+                                                Window* window) = 0;
+  virtual void OnDidRestackTransientChildAbove(Window* source,
+                                               Window* window) = 0;
+
  protected:
   virtual ~TransientWindowClientObserver() {}
 };