Converts overview to use common ash types

ash/wm/common/wm_shell_window_ids.h

 // Copyright 2016 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 ASH_WM_COMMON_WM_SHELL_WINDOW_IDS_H_
 #define ASH_WM_COMMON_WM_SHELL_WINDOW_IDS_H_
 
 // Defines the ids assigned to known containers. The id for a WmWindow is
 // accessed via GetShellWindowId().
 
@@ skipping 34 matching lines @@
 
 // The container for the lock screen modal windows.
 const int kShellWindowId_LockSystemModalContainer = 16;
 
 // The container for menus.
 const int kShellWindowId_MenuContainer = 19;
 
 // The container for drag/drop images and tooltips.
 const int kShellWindowId_DragImageAndTooltipContainer = 20;
 
+// The container for special components overlaid onscreen, such as the
+// region selector for partial screenshots.
+const int kShellWindowId_OverlayContainer = 22;
+
 // ID of the window created by PhantomWindowController or DragWindowController.
 const int kShellWindowId_PhantomWindow = 23;
 
 }  // namespace ash
 
 #endif  // ASH_WM_COMMON_WM_SHELL_WINDOW_IDS_H_