Add persisted preference for projection touch HUD

ash/shell.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_H_
 #define ASH_SHELL_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 444 matching lines @@
     return root_window_host_factory_.get();
   }
 
   LauncherModel* launcher_model() {
     return launcher_model_.get();
   }
 
   // Returns the launcher delegate, creating if necesary.
   LauncherDelegate* GetLauncherDelegate();
 
-  void SetTouchHudProjectionEnabled(bool enabled);
-
-  bool is_touch_hud_projection_enabled() const {
-    return is_touch_hud_projection_enabled_;
-  }
+  // Called when the preference for projection touch HUD is changed. It will
+  // show or hide the HUD based on the new preference value.
+  void TouchHudProjectionEnabledChanged(bool enabled);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ExtendedDesktopTest, TestCursor);
   FRIEND_TEST_ALL_PREFIXES(WindowManagerTest, MouseEventCursors);
   FRIEND_TEST_ALL_PREFIXES(WindowManagerTest, TransformActivate);
   friend class internal::RootWindowController;
   friend class test::ShellTestApi;
   friend class shell::WindowWatcher;
 
   typedef std::pair<aura::Window*, gfx::Rect> WindowAndBoundsPair;
@@ skipping 123 matching lines @@
   views::corewm::CursorManager cursor_manager_;
 
   ObserverList<ShellObserver> observers_;
 
   // Used by ash/shell.
   content::BrowserContext* browser_context_;
 
   // For testing only: simulate that a modal window is open
   bool simulate_modal_window_open_for_testing_;
 
-  bool is_touch_hud_projection_enabled_;
-
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_H_