Handle UNPIN operation in ash.

ash/accelerators/accelerator_commands.h

 // Copyright 2013 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_ACCELERATORS_ACCELERATOR_COMMANDS_H_
 #define ASH_ACCELERATORS_ACCELERATOR_COMMANDS_H_
 
 #include "ash/ash_export.h"
 
 // This file contains implementations of commands that are bound to keyboard
@@ skipping 19 matching lines @@
 
 // True if the desktop zoom accelerator is enabled.
 bool IsInternalDisplayZoomEnabled();
 
 // Change internal display zooming up or down.
 ASH_EXPORT bool ZoomInternalDisplay(bool up);
 
 // Reset the display zooming to the default state.
 ASH_EXPORT void ResetInternalDisplayZoom();
 
+// If it is in the pinned mode, exit from it.
+ASH_EXPORT void Unpin();
+
 }  // namespace accelerators
 }  // namespace ash
 
 #endif  // ASH_ACCELERATORS_ACCELERATOR_COMMANDS_H_