Remove now-unnecessary wrappers around gfx::Screen::GetScreen()

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 191 matching lines @@
   // has a launcher.
   static aura::Window* GetPrimaryRootWindow();
 
   // Returns a root Window when used as a target when creating a new window.
   // The root window of the active window is used in most cases, but can
   // be overridden by using ScopedTargetRootWindow().
   // If you want to get the root Window of the active window, just use
   // |wm::GetActiveWindow()->GetRootWindow()|.
   static aura::Window* GetTargetRootWindow();
 
-  // Returns the global Screen object that's always active in ash.
-  static gfx::Screen* GetScreen();
-
   // Returns all root windows.
   static aura::Window::Windows GetAllRootWindows();
 
   static aura::Window* GetContainer(aura::Window* root_window,
                                     int container_id);
   static const aura::Window* GetContainer(const aura::Window* root_window,
                                           int container_id);
 
   // Returns the list of containers that match |container_id| in
   // all root windows. If |priority_root| is given, the container
@@ skipping 540 matching lines @@
   scoped_ptr<GPUSupport> gpu_support_;
 
   base::SequencedWorkerPool* blocking_pool_;
 
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_H_