Change overview mode to so that docked panel windows are not grouped together.

ash/wm/overview/transparent_activate_window_button.h

Index: ash/wm/overview/transparent_activate_window_button.h
diff --git a/ash/wm/overview/transparent_activate_window_button.h b/ash/wm/overview/transparent_activate_window_button.h
index 0fe374732cd1058ece4b6b1d4b27b38d73b48acb..9dac693c5b3782ca425175442ecab764d4bc9ccb 100644
--- a/ash/wm/overview/transparent_activate_window_button.h
+++ b/ash/wm/overview/transparent_activate_window_button.h
@@ -42,9 +42,6 @@ class TransparentActivateWindowButton {
   // window title is read.
   void SendFocusAlert() const;
 
-  // Stacks |this| above |activate_button| in the window z-ordering.
-  void StackAbove(TransparentActivateWindowButton* activate_button);
-
  private:
   // The transparent window event handler widget itself.
   scoped_ptr<views::Widget> event_handler_widget_;