Add persisted preference for projection touch HUD

ash/shell_delegate.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 ASH_SHELL_DELEGATE_H_
 #define ASH_SHELL_DELEGATE_H_
 
 #include <string>
 
 #include "ash/ash_export.h"
@@ skipping 240 matching lines @@
 
   // Creates a menu model of the context for the |root_window|.
   virtual ui::MenuModel* CreateContextMenu(aura::RootWindow* root_window) = 0;
 
   // Creates a root window host factory. Shell takes ownership of the returned
   // value.
   virtual RootWindowHostFactory* CreateRootWindowHostFactory() = 0;
 
   // Get the product name.
   virtual base::string16 GetProductName() const = 0;
+
+  // Returns if the projection touch HUD is enabled or not.
+  virtual bool IsTouchHudProjectionEnabled() const = 0;
+
+  // Invoked to toggle the projection touch HUD.
+  virtual void ToggleTouchHudProjection() = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_DELEGATE_H_