Fix Z-order for a bubble when it appears for inactive window.

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.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_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_
 
 #include <X11/extensions/shape.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
@@ skipping 83 matching lines @@
   scoped_ptr<corewm::Tooltip> CreateTooltip() override;
   scoped_ptr<aura::client::DragDropClient> CreateDragDropClient(
       DesktopNativeCursorManager* cursor_manager) override;
   void Close() override;
   void CloseNow() override;
   aura::WindowTreeHost* AsWindowTreeHost() override;
   void ShowWindowWithState(ui::WindowShowState show_state) override;
   void ShowMaximizedWithBounds(const gfx::Rect& restored_bounds) override;
   bool IsVisible() const override;
   void SetSize(const gfx::Size& requested_size) override;
+  void StackAbove(aura::Window* window) override;
   void StackAtTop() override;
   void CenterWindow(const gfx::Size& size) override;
   void GetWindowPlacement(gfx::Rect* bounds,
                           ui::WindowShowState* show_state) const override;
   gfx::Rect GetWindowBoundsInScreen() const override;
   gfx::Rect GetClientAreaBoundsInScreen() const override;
   gfx::Rect GetRestoredBounds() const override;
   gfx::Rect GetWorkAreaBoundsInScreen() const override;
   void SetShape(gfx::NativeRegion native_region) override;
   void Activate() override;
@@ skipping 236 matching lines @@
   base::CancelableCallback<void()> delayed_resize_task_;
 
   base::WeakPtrFactory<DesktopWindowTreeHostX11> close_widget_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostX11);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_