Make PrefService available in *ash

ash/shell/shell_delegate_impl.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_SHELL_DELEGATE_IMPL_H_
 #define ASH_SHELL_SHELL_DELEGATE_IMPL_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 29 matching lines @@
   SystemTrayDelegate* CreateSystemTrayDelegate() override;
   std::unique_ptr<WallpaperDelegate> CreateWallpaperDelegate() override;
   SessionStateDelegate* CreateSessionStateDelegate() override;
   AccessibilityDelegate* CreateAccessibilityDelegate() override;
   std::unique_ptr<PaletteDelegate> CreatePaletteDelegate() override;
   ui::MenuModel* CreateContextMenu(WmShelf* wm_shelf,
                                    const ShelfItem* item) override;
   GPUSupport* CreateGPUSupport() override;
   base::string16 GetProductName() const override;
   gfx::Image GetDeprecatedAcceleratorImage() const override;
+  PrefService* GetActiveUserPrefService() const override;
   bool IsTouchscreenEnabledInPrefs(bool use_local_state) const override;
   void SetTouchscreenEnabledInPrefs(bool enabled,
                                     bool use_local_state) override;
   void UpdateTouchscreenStatusFromPrefs() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ShellDelegateImpl);
 };
 
 }  // namespace shell
 }  // namespace ash
 
 #endif  // ASH_SHELL_SHELL_DELEGATE_IMPL_H_